A controversy over bias within the party leadership favouring Hillary Clinton on Sunday rocked the Democratic Party on the eve of its national convention in Philadelphia.

The head of the party announced her resignation after the publication of emails that indicated party leaders had preferred Clinton over rival Bernie Sanders during the primaries.

The emails, which were part of a hack into the Democratic National Committee (DNC) last year, appeared to confirm the bias that Sanders, a US senator from Vermont, had long accused the party leadership of holding.

The situation raised the possibility that Wasserman Schultz could be booed when she opens the convention on Monday just as the party is trying to unify behind Clinton.

Wasserman Schultz said in a statement that she remained committed to helping Clinton win the White House, but "going forward, the best way for me to accomplish those goals is to step down as party chair at the end of this convention."

She said she would fulfill her role and open and close the convention and address delegates "about the stakes involved in this election not only for Democrats, but for all Americans."

During the primaries she had denied the DNC favoured one candidate over another.

Clinton thanked Wasserman Schultz for her leadership of the DNC over the past five years.

"I know that this week's events will be a success thanks to her hard work and leadership," Clinton said in a statement.

US President Barack Obama also praised Wasserman Schultz, saying that during her tenure she "has had my back." He said her leadership "has meant that we had someone who brought Democrats together not just for my re-election campaign, but for accomplishing the shared goals we have had for our country."

Obama also said he had called her earlier Sunday.

Clinton's Republican opponent, Donald Trump, wasted no time in commenting on the situation on Twitter. He referred to a "rigged system" that pushed Clinton over the top.

"The highly neurotic Debbie Wasserman Schultz is angry that, after stealing and cheating her way to a Crooked Hillary victory, she's out!" Trump crowed.

Sanders stayed in the race through the final primary after putting up a surprisingly strong challenge to the former US secretary of state. The hacked emails were published by the whistleblowing website WikiLeaks.

In one of the emails a high-ranking member of the party leadership suggests Sanders' religious beliefs should be used against him in states with high numbers of Christian voters. Sanders was raised in a Jewish family and during the campaign described himself as "not particularly religious."

Sanders, who earlier Sunday called for Wasserman Schultz's resignation, last month announced the suspension of his campaign and said he supported Clinton. He is scheduled to speak on Monday evening.

Sanders issued a statement calling for a new direction for the party that would welcome the working class and young voters and that would remain neutral in future Democratic primary contests.

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.