Syrian government forces and allied militias have clashed with rebels near the capital, Damascus, just hours after a nationwide truce officially took effect, a monitoring group and a rebel official say.
The Britain-based Syrian Observatory for Human Rights said on December 30 it was not clear who had started the fighting in Wadi Barada, a rebel-held valley northwest of Damascus. Government helicopters were firing on the area, the observatory added.
A rebel official also reported clashes in the area, according to the Reuters news agency.
The observatory also said that government warplanes carried out at least 16 air strikes against rebels in the northeastern province of Hama on December 30. It did not immediately report any casualties.
The truce brokered by Russia and Turkey came into force at midnight and is the first nationwide halt in fighting since a week-long cease-fire in September that collapsed after several incidents of violence.
Russia's UN Ambassador Vitaly Churkin said he would formally present the draft during closed Security Council consultations on December 30 and that he hopes the council will unanimously adopt the resolution at a meeting on December 31.
He said the Security Council needs to participate "in this important process."
Earlier in the day, the observatory said that while most of the country was calm overnight, "fierce clashes" took place between rebels and government forces in the northeastern province of Hama.
Abdel Rahman, the head of the monitoring group, told the AFP news agency, "Small rebel groups and armed loyalists are seeking to destroy the truce because it puts an end to their presence."
Russian President Vladimir Putin, a key ally of Syrian President Bashar al-Assad, announced on December 29 that the Syrian government and groups that oppose it had signed the agreement on a nationwide cease-fire.
Putin said a document outlining measures to enforce the cease-fire was also signed, and Russia says that Moscow and Ankara are "guarantors" of the truce.
Putin also said that the government and opponents had signed a separate declatation voicing their readiness to hold talks aimed to end the nearly six-year civil war.
Russia is seeking to organize those negotiations soon in Astana, the capital of Kazakhstan. Russian Foreign Minister Sergei Lavrov discussed those plans with the new Kazakh foreign minister, Kairat Abdrakhmanov, by telephone on December 30.
The cease-fire does not apply to combat against the extremist group Islamic State (IS) and the Al-Nusra Front, which now calls itself the Fateh al-Sham Front and says it is no longer affiliated with Al-Qaeda.
The announcement came days after Syrian government forces took full control of the northern city of Aleppo, forcing out rebels who had held the eastern part of the city since 2012.
More than 250,000 people have been killed and many more driven from their homes in the Syrian civil war, which began with a deadly government crackdown on pro-democracy protesters opposed to Assad in 2011.