The United States and Russia early Saturday announced an agreement on a plan to reduce violence in Syria, calling for a ceasefire starting at sundown on Monday and a move towards a political transition.

US Secretary of State John Kerry, speaking after more than 12 hours of consultations with Russian Foreign Minister Sergei Lavrov, said the deal could provide a "turning point" in the conflict if the parties implement it "in good faith."

"Working together, Russia and the United States and our teams, have devised what we think is a more prescriptive and far-reaching approach than we have been able to put together to date," Kerry said.

The plan would ensure that the Russian-backed Syrian government does not fly combat missions over rebel-held areas, which would allow humanitarian aid to reach people in need.

With Syrian government airstrikes halted, there's a potential to "change the nature of the conflict," Kerry said, noting that the strikes have been the main driver of casualties and migration flows.

The US and Russia also agreed on specific areas where the two countries will fight together against Islamic State extremists, Lavrov said.

He also said Russia had spoken to the Syrian government which had given its support for the agreement.

A spokesman for the High Negotiations Committee, a Syrian rebel umbrella group, told Russian news agency Tass that it would support the agreement if Syrian regime troops also respected the ceasefire.

UN envoy for Syria Staffan de Mistura welcomed the agreement and said he hoped the deal would help "renewed efforts to reach aSyrian-owned and Syrian-led political settlement of the conflict."

All sides will need to adhere to the cessation of hostilities for seven days before the plan can fully go into effect. Preparatory work to delineate areas held by the government, rebels and terrorists will also commence on Monday.

Kerry stressed that the US and Russia will carry out joint military strikes against terrorists only if there's a sustained period of reduced violence.

The meeting between the top US and Russian diplomats in Geneva had focused on achieving a durable ceasefire and stepping up humanitarian aid, according to the White House and diplomatic sources.

The US supports the opposition that is fighting to oust Syrian President Bashar al-Assad, an ally of Russia.

In February, after nearly five years of conflict, the US and Russia brokered a nationwide ceasefire in Syria.

It held for a time but then collapsed under the pressure of localized fighting and a failed UN-backed political process to end the violence.

There have been attempts since to reach short-term, often region-specific, cessations of hostilities, but these have tended to be short-lived.

Russia has emphasized the possibility of reaching a deal with Washington on military collaboration against terrorist groups in the country.

Russia's Foreign Ministry said Kerry and Lavrov discussed the possibility during a phone call on Thursday.

The conflict in Syria has intensified in recent months, worsening the humanitarian situation in the country.

Al-Assad’s forces and allied paramilitaries this week regained territory from rebels in the divided northern city of Aleppo.

The advance has allowed regime forces to impose a siege on Aleppo’s eastern rebel-held section, putting the fate of an estimated 250,000 to 300,000 residents there in jeopardy.

A UN humanitarian official warned on Friday that the situation in eastern Aleppo was “extremely severe.”

"Therefore, we continue to demand a 48-hour weekly humanitarian pause to reach the people in need," the UN's humanitarian affairs chief, Stephen O'Brien, said in Geneva.

Once Syria’s commercial hub, Aleppo has been divided between al-Assad's forces in the west and rebels to the east since fighting for control of the city erupted in mid-2012.

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.