France has called on Russia to stop military action in Syria and respect a fragile ceasefire agreement brokered by Moscow and Turkey to end almost six years of war.
The truce deal, which was welcomed unanimously by the United Nations Security Council, has been repeatedly violated since it began, with warring sides trading the blame.
On Saturday, Syria rebels warned they would abandon the ceasefire if government forces continued to violate it, asking the Russians, who support President Bashar al-Assad, to rein in army and militia attacks in the valley by 8 pm.
French Prime Minister Bernard Cazeneuve said: "We resolutely condemn everything Russia could do in Syria that would contribute to a continuation of fighting.
"We hope talks between separate Syrian forces will continue so the ceasefire can hold. We ask the Russians to stop taking part in military operations which are deadly operations."
However he did not specify which actions in particular he was referring to.
Russia's capital Moscow celebrated the start of 2017 with a firework display over Red Square.
Despite rain and fog, revellers gathered to watch the pyrotechnic spectacular, with some people watching from boats.
The United Nations has adopted a resolution supporting efforts by Russia and Turkey to end violence in Syria and start peace negotiations.Read the full story ›
Syrian rebel groups have said that they would consider a ceasefire deal brokered by Russia and Turkey "null and void" if government forces and their allies continued to violate it.
Airstrikes and clashes have continued in some areas since the ceasefire officially began on Friday.
A statement signed by a number of rebel groups said: "Continued violations by the regime and bombardment and attempts to attack areas under the control of the revolutionary factions will make the agreement null and void."
Alleged Russian hacking of the US should be considered "an act of war", Republican Senator John McCain has said.
Mr McCain said a lot more needs to be done in response to the hacks, saying America needs to make sure there is a price to pay.
The former presidential candidate made the remarks after President Barack Obama's administration unleashed a string of sanctions and ordered that 35 Russians be expelled from the US amid allegations of Russian meddling in the American presidential election.
"When you attack a country, it's an act of war," Mr McCain said on a visit to Kiev.
"And so we have to make sure that there is a price to pay, so that we can perhaps persuade the Russians to stop these kind of attacks on our very fundamentals of democracy."
Mr McCain said it was possible to impose many sanctions on Russia, including financial institutions, individuals and organisations.
He has scheduled a hearing for Thursday on foreign cyber threats.
Donald Trump has appeared to praise President Vladimir Putin for not expelling US diplomats from Russia.
Hours after Mr Putin said he would not retaliate to Barack Obama's decision to throw 35 Russian officials out of the US over allegations of hacking, Mr Trump tweeted: "Great move on delay (by V. Putin) - I always knew he was very smart!"
Great move on delay (by V. Putin) - I always knew he was very smart!
President Vladimir Putin was expected to expel dozens of diplomats today in response to President Barack Obama throwing 35 Russian officials out of the US over allegations of hacking.
But despite calls for action from his own foreign ministry, he said he would not stoop to the level of the Americans and that he would work to restore relations once Donald Trump is in the White House.
US foreign policy analyst James Jeffrey told ITV News: "This is just typical Putin having a good time."
- Video report by ITV News Correspondent Martin Geissler
A hearing into foreign cyber threats to the United States has been scheduled by Republican Senator John McCain.
The announcement comes after 35 Russian diplomats were given 72 hours to leave America in retaliation to alleged hacking during November's presidential election.
The hearing will take place on Thursday, with witnesses called to testify include Director of National Intelligence James Clapper and Admiral Mike Rogers, head of the US Cyber Command.
Russian President Vladimir Putin said that he hopes when President-elect Donald Trump takes office, Moscow and Washington will be able to take "real steps" to improve relations between the two countries.
Putin made the comments in a New Year's congratulatory message to Trump, and comes after a tense few days in which the US accused Russian intelligence agencies of being involved in hacking around the US election, and issued further sanctions.
Putin also added that positive developments in relations between Russia and Britain would be mutually beneficial.
President Vladimir Putin says Russia won't be expelling US diplomats in response to a new round of US sanctions, which includes 35 Russian diplomats begin given 72 hours to leave the country.
In withering comments, he criticised the US sanctions, saying he would wait for Donald Trump to be inaugurated before deciding on further action, and even invited US diplomats and their families to a party in the Kremlin.
In a statement on Friday, he said: "We will not expel anyone. While keeping the right for retaliatory measures, we will not descend to the level of 'kitchen', irresponsible diplomacy.
"Further steps towards the restoration of Russian-American relations will be built on the basis of the policy which the administration of President D. Trump will carry out."
He also said the government would not seek to bar US diplomats from their usual holiday spots, adding: "Moreover, I invite all children of American diplomats accredited in Russia to the New Year and Christmas party in the Kremlin."