The United States has welcomed a ceasefire agreement aimed at ending the war in Ukraine but demanded that Russia end its support for the separatists.
US Secretary of State John Kerry said sanctions on Russia could be eased but only if its actions matched its words.
The leaders of Russia, Ukraine, Germany and France sealed a deal on Thursday morning after lengthy talks in Belarus.
The ceasefire is due to begin in eastern Ukraine at midnight on Saturday but both sides remain sceptical.
Pro-Russian rebels have signed the agreement, which also includes weapon withdrawals and prisoner exchanges, but key issues remain to be settled.
Clashes between government forces and the rebels continued on Thursday and one Russian-backed commander said his forces would not stop fighting.
Thousands of people have died in almost a year of fighting in the region.
In another development, the World Bank said on Thursday that it is ready to provide up to $2 billion (£1.3bn) in financial assistance to Ukraine this year as part of an international package of support.
people killed since conflict began in April 2014
- 12,972 wounded across eastern Ukraine
- 5.2 million people estimated to be living in conflict areas
- 978,482 internally displaced people within Ukraine, including 119,832 children
On the ground: James Reynolds, BBC News, Donetsk
Tonight, the centre of this rebel heartland is quieter than before. The sound of artillery fire in the distance has become more sporadic, but it hasn’t entirely ended.
Donetsk remains a semi-deserted city. Many residents who remember the failure of last September’s ceasefire agreement will spend the night in their basements and shelters.
One local told me he hoped the ceasefire would work but said he wanted to remain as “New Russia” in the future. “There are only a handful of people who will want to be part of Ukraine,” he said.
Rebel forces continue to hold their checkpoints and positions and see no immediate need to retreat. One fighter said he didn’t trust the other side to stop shooting. Others have told the BBC that they will carry on fighting in the name of their fellow soldiers who have been killed.
‘A good morning’
Ukrainian President Petro Poroshenko said implementation of the agreement, reached by leaders in the Belarusian capital Minsk, would be difficult.
A key sticking point is the disputed town of Debaltseve, a key government-held town surrounded by rebels, where fighting is still going on.
Further talks will also be held on self-rule in parts of Donetsk and Luhansk separatist regions.
The latest agreement includes:
- Ceasefire to begin at 00:01 local time on 15 February
- Heavy weapons to be withdrawn, beginning on 16 February and completed in two weeks
- All prisoners to be released; amnesty for those involved in fighting
- Withdrawal of all foreign troops and weapons from Ukrainian territory. Disarmament of all illegal groups
- Ukraine to allow resumption of normal life in rebel areas, by lifting restrictions
- Constitutional reform to enable decentralisation for rebel regions by the end of 2015
- Ukraine to control border with Russia if conditions met by the end of 2015
Speaking after the 16-hour talks ended, Mr Putin told Russian television: “It wasn’t the best night for me, but it’s a good morning.”
Mr Putin announced the ceasefire at a news conference in Minsk
German Chancellor Angela Merkel said it offered a “glimmer of hope”, while French President Francois Hollande said “the coming hours will be decisive”.
The White House welcomed the agreement as a “potentially significant step” but expressed concern over reports of continued fighting in eastern Ukraine.
“All the parties must show complete restraint in the run-up to the Sunday ceasefire, including an immediate halt to the Russian and separatist assault on Debaltseve and other Ukrainian towns,” Mr Kerry said in a statement.
Separatists gave the agreement a cautious welcome but Donetsk rebel leader Alexander Zakharchenko said Kiev would be to blame if the deal collapsed and warned that there would “be no meetings and no new agreements”.
Mr Poroshenko – who had accused Russia of making “unacceptable” demands – said rebels had launched an offensive after the agreement was announced.
The renewed fighting came after Ukrainian military officials said on Thursday that 50 Russian tanks, as well as armoured vehicles and rocket launchers, had crossed into Ukraine.
Ukraine and the West accuse Russia of supplying weapons and personnel to the rebels, but Russia denies this.
More than 5,400 people have been killed since the conflict began. There has been a dramatic rise in casualties in recent days, with 263 civilians killed in populated areas between 31 January and 5 February.
Source: BBC News