Thailand's King Bhumibol Adulyadej, the world's longest reigning monarch, died on Thursday at age 88, the royal household said in a statement.

No cause of death was given. The statement said that "doctors [at Siriraj Hospital] treated the ailing king to the best of their ability, but the king's health continued to deteriorate before he passed away peacefully."

The time of death was given as 3:52 pm (0852 GMT).

The king had spent much of his time since 2009 in Siriraj, where he continued to perform his largely ceremonial duties as head of state. His last public appearance was in January.

Bhumibol was a beloved and unifying figure in Thailand, whose 70 years on the throne provided a consistent backdrop of stability to the frequent turbulence of Thai politics.

Revered by Thais as semi-divine, the king enjoyed near-universal admiration. His portrait is ubiquitously displayed throughout the country in gilded tributes along roadsides, in shops, homes and official buildings, and on coins and paper currency.

His reign exceeded those of Queen Victoria of Britain (63 years) and Emperor Hirohito of Japan (62 years), making Bhumibol's tenure as head of state one of the longest in recorded history.

Born on December 5, 1927 in Cambridge, Massachusetts, Bhumibol was the second son of Prince Mahidol, Thailand's "father of modern medicine," who was studying public health at Harvard University at the time of Bhumibol's birth.

Bhumibol grew up mostly abroad, spending his formative years in Lausanne, Switzerland.

His elder brother, King Ananda Mahidol, died under mysterious circumstances in 1946, bringing the shy young Bhumibol to the throne at a time of political uncertainty, only 14 years after the country's 700-year absolute monarchy was ended by a military coup.

Bhumibol ascended to the throne on June 6, 1946.

Many Thai leaders then considered the monarchy to be an archaic institution, but the rise of communism in South-East Asia led Thailand's military dictators in the 1950s and 1960s to elevate the role of the king in an attempt to counter a growing insurgency.

Old ceremonies from the days of absolute monarchy were reinstituted and widely promoted, and Bhumibol led official rituals to mark important religious and political events.

Bhumibol was also sent on a worldwide tour in 1960, in which he and his wife, the fashionable Queen Sirikit, visited 23 countries, including the United States and most European capitals.

The tour was well received in Thailand, and images of Bhumibol playing saxophone with Benny Goodman and socializing with Elvis Presley adorn the homes of many Thais to this day.

Bhumibol also became the first Thai monarch to visit the distant reaches of his kingdom, winning his subjects' hearts with his humble and personal approach, and through the outreach programmes he championed to help alleviate the sufferings of the poor.

During the years of military-dominated politics and 17 coups d'etat between 1932 and 1991, Bhumibol developed a low-profile political style and saviour-of-last-resort role that arguably brought the country through its worst periods of crisis.

"Thais, in general, willingly and unreservedly accord him the confidence and trust that no other monarch in our history, or for that matter any other monarch in the world, has ever enjoyed," former prime minister Anand Panyarachun said in a 1996 speech.

The king's popularity derived from his dedication to rural development projects, strict adherence to Buddhist precepts and a commitment to the common good.

In 1992, the king famously ended a confrontation between pro-democracy demonstrators and the military by calling in the two chief protagonists - former army commander-in-chief Suchinda Krapayoon and politician Chamlong Srimuang - for a personal audience.

In a televised broadcast, the two knelt before Bhumibol like naughty schoolboys receiving a scolding. The king's actions ended the bloody street fighting that had claimed at least 44 lives and brought Thailand to the verge of political chaos.

In recent years, Bhumibol increasingly spent time outside the public eye, resting in the palace and being treated in hospital.

A strict lese majeste law seeking to protect the king's image was enforced more regularly, and successive governments oversaw a dramatic rise in such cases, with some leading to lengthy prison sentences of up to 15 to 20 years.

Academics and commentators have long called for the law's repeal, saying it is widely abused and used as a tool simply to silence government critics and political opponents.

Critics of the law also cite a 2005 speech in which Bhumibol himself said he should not be above criticism.

Despite the rise in lese majeste cases in recent years, Bhumibol remained enormously popular in Thailand, where both sides of the deeply divided country long viewed him as a stabilizing figurehead.

The king's death immediately raised the delicate question of royal succession. Bhumibol is survived by his wife Queen Sirikit, his son, Crown Prince Vajiralongkorn, and three daughters.

Prince Vajiralongkorn, 64, does not command the same respect among Thais that his father did.

Related stories

Thailand enters mourning period after death of King Bhumibol

Thailand's crown prince becomes King Rama X

Coronation of next Thai king could be delayed by one year

Latest news

Syrian opposition rules out future role for President al-Assad

The Syrian opposition said Friday it would not accept any role for President Bashar al-Assad in the future of the war-torn country, reacting to a recent US shift saying that removing al-Assad is no longer a priority for Washington.

Russian Army integrates breakaway forces of Georgian province

Parts of the small fighting forces of the Georgian breakaway province of South Ossetia have been placed under Russian military control, Russian Defence Minister Sergei Shoigu said on Friday.

Czech Republic's Pilsner Urquell beer is now Japanese

Japanese brewing company Asahi completed its takeover of the Czech brewery Pilsner Urquell on Friday, Asahi said in a statement.

Judge approves 25-million-dollar settlement of Trump University case

A US district judge on Friday approved a 25-million-dollar settlement of lawsuits and state fraud allegations against Trump University, the US president's now-defunct business venture.

Former Thai premier Thaksin to junta on reconciliation: 'Cut me out'

Former Thai prime minister Thaksin Shinawatra on Friday announced that he is not interested in the junta-led reconciliation process, three days after the junta handed him a half-a-billion-dollar tax bill for his past business deal.

Dalic: We welcome possible deal between Agrokor and banks

The government welcomes the possibility of an agreement being concluded between the Agrokor food company and creditor banks, and the bill on vitally important companies is not a fallback plan but the result of the government's care for the overall economic and financial stability of Croatia, Deputy Prime Minister and Minister of Economy Martina Dalic told a press conference in Zagreb on Friday.

Croatia, China sign action plan for cooperation in agriculture

The Croatian and Chinese ministries of agriculture on Friday signed an action plan for cooperation in the field of agriculture for the period 2017-2018, the Croatian ministry said in a statement.

ZSE indices up, Agrokor shares in focus of investor interest

The Zagreb Stock Exchange (ZSE) indices on Friday rose by more than 1.8%, with stocks of the Agrokor food and retail concern being in the focus of investor interest again.

Berlin police defend handling of Berlin market attacker

Berlin police defended themselves on Friday against accusations that they stopped surveillance on Berlin Christmas market attacker despite knowing in June 2016 he was dangerous.

Croatia, creditors tailor emergency measures to save tottering giant

Croatia's tottering retail and food giant Agrokor reached an agreement with its creditors, putting its debts standby and allowing it to continue working during emergency restructuring, the Croatian branch of Austria's Erste Bank said Friday.

Agrokor's creditors say standstill agreement to go into force today

A standstill agreement regarding the Agrokor concern's existing financial obligations to banks will take effect on Friday, additional capital will be injected into the concern in the coming days and the concern will be actively restructured, which includes a change of its management, it was said on Friday after a meeting between Agrokor's suppliers and creditor banks.

Palestinians, UN slam Israel's new settlement plan

Palestinians, Israeli activists and the UN lambasted the government of Israeli Prime Minister Benjamin Netanyahu on Friday, a day after it gave the go-ahead for the first new West Bank settlement in a quarter of a century.

South Sudan rebels release three abducted foreign oil workers

South Sudanese rebels have released three foreign engineers they abducted in early March in the oil-rich Upper Nile region, Foreign Affairs Ministry official Mawein Makol Arik said on Friday.

Turkish opposition: Imprisoned party chief has gone on hunger strike

The head of Turkey's pro-Kurdish opposition party has launched a hunger strike from prison.

European leagues threaten Champions League schedule clashes

The European Professional Football Leagues (EPFL) on Friday threatened schedule clashes on Champions League matchdays in an ongoing dispute with the governing body UEFA.

Danish court revokes citizenship of IS volunteer

A Danish appellate court on Friday stripped a man of his Danish citizenship for volunteering to fight for the extremist Islamic State in Syria.

Banks and Agrokor agree on key elements of standstill agreement

Member banks of the coordinating committee of financial creditors and representatives of the Agrokor food company have in principle agreed on key elements of a standstill agreement, which is expected to be signed later today, announcing changes in the company's management team, Erste Bank said in a statement on Friday afternoon.

Syrian man on trial in Sweden; mosque attack labelled terrorism

A Syrian man went on trial Friday in the southern Swedish city of Malmo, charged with terrorism and arson after an attack last year on a building used as an assembly hall by Shiite Muslims.