German Chancellor Angela Merkel has said a bid to resolve the Ukrainian conflict is “uncertain but worth trying,” as the French President warned it was “one of the last chances” for peace.
Speaking at a security conference in Munich, Ms Merkel also said Russia “needs to do its bit” to resolve the crisis.
She accused Moscow of showing “territorial disrespect” for its neighbour, and said international law had been violated.
Her comments come after she and French President Francois Hollande met Russian leader Vladimir Putin in Moscow, in what was widely seen as a last-ditch attempt to thrash out a deal to end fighting which has claimed the lives of more than 5,300 people.
Mr Hollande said the agreement could include a demilitarised zone and greater autonomy for the separatist eastern region.
Ms Merkel said of the peace efforts: “It is uncertain whether it will lead to success, but from my point of view and that of the French President it is definitely worth trying.”
Mr Hollande told reporters: “I think this is one of the last chances, that’s why we took this initiative.”
Asked at the talks whether he thought the peace proposal could work, Ukrainian President Petro Poroshenko replied: “Yes.”
However he rejected any changes to territorial lines set out in a peace deal agreed in Minsk last September.
The rebels have made big gains since then, raising doubts whether they will respect the pact in its existing form.
Mr Putin said Russia does not want war, but he was scathing of Western sanctions over Ukraine.
He told trade union members in Moscow: “There’s no war, thank God. But there is definitely an attempt to curb our development.”
He added: “But we don’t plan to fight a war with anyone, we plan to cooperate with everyone.”
But US Vice President Joe Biden called on Mr Putin to demonstrate this by his actions.
The West has accused Russia of sending troops and weapons across the border although Moscow has consistently denied backing the rebels.
“Given Russia’s recent history we need to judge its deeds not its words,” Mr Biden told the conference. “Don’t tell us, show us, President Putin,” he added.
Addressing the conference, Mr Poroshenko brandished several passports taken from Russian soldiers in what he claimed was proof of Moscow’s “presence” in his country.
“This is the best evidence for the aggression and for the presence of Russian troops,” he said.
Amid a debate in Washington over whether to send weapons to help Kiev fight pro-Russian rebels, the German Chancellor argued this would not help end the crisis.
But NATO’s top military commander has said this should not be ruled out.
US Air Force General Philip Breedlove told reporters at the Munich conference: “I don’t think we should preclude out of hand the possibility of the military option.”
Clashes between the separatists and Ukrainian forces in the east of the country have escalated in recent weeks, despite the Minsk pact.
A spokesman for the Ukrainian military said five soldiers had been killed in the last 24 hours alone, while separatists appeared to be amassing for new offensives on the key railway town of Debaltseve and the coastal city of Mariupol.
There are also fears of a growing humanitarian crisis in the country.