There is "no good news yet" from a marathon four-way peace summit in Minsk, Ukrainian President Petro Poroshenko has said, as Russia is imposing "unacceptable" conditions.
"Unfortunately there's no good news yet," Poroshenko told AFP news agency on Thursday of the talks involving the leaders of Russia, Ukraine, France and Germany.
"There are conditions that I consider unacceptable," he said, declining to elaborate. "The (negotiations) process is ongoing," he said during a brief break after over 14 hours of talks in the Belarus capital.
"There's always hope," Poroshenko said of the last-ditch bid to end 10 months of bloodshed that has killed over 5,300 people.
"We're in non-stop talks, as you can see, the situation is very difficult, (German Chancellor) Angela Merkel and (French) President Francois Hollande are helping us a lot, but for now the situation is difficult."
While the talks dragged on in Minsk, at least nine people were killed and 35 more wounded in fresh fighting in eastern Ukraine, officials said on Thursday.
"As a result of shelling and clashes two Ukrainian soldiers were killed, 21 more were wounded," Vladyslav Seleznyov, spokesman for Ukraine's General Staff, told reporters.
Separately, the city administration in rebel-held Donetsk said seven people were killed and 14 wounded in the fighting.
"The night of 11 to 12 February in Donetsk was tense," the administration said. "Powerful explosions and salvos could be heard periodically," it said.
Despite the fresh violence, the negotiations in Minsk opened on Wednesday evening with a handshake between Poroshenko and Russian leader Vladimir Putin, who were meeting for the first time since October.
"Today the peace process for Ukraine is all about Minsk and I hope that the meeting will fulfil our best expectations," Poroshenko told host Belarusian leader Alexander Lukashenko ahead of the talks.
Poroshenko warned before the talks that he would introduce martial law throughout the country if they fail to stop a war that has already claimed more than 5,300 lives.
Martial law would mark a significant escalation of the crisis, freeing up military resources for the fight in the east but also likely leading to the severance of foreign investment for cash-strapped Ukraine.
Poroshenko was scheduled to brief a European Union summit in Brussels on Thursday.
If the Minsk talks fail, US President Barack Obama has warned that Washington may decide to start providing lethal weapons to Ukraine, a step many European leaders oppose for fear of getting drawn into open conflict with Russia.
Separatist negotiators meanwhile met on Wednesday elsewhere in Minsk to agree how to implement previous truce deals with representatives from Kiev, Moscow and mediators from the Organization for Security and Co-operation in Europe.
The most pressing element is the need to agree on an immediate ceasefire between the two sides that would see an end to the surge in fighting that has killed hundreds of civilians in recent weeks.
A key sticking point is whether a new deal will extend rebel control over 500sq km (200 square miles) of territory taken over the past month.
Moscow is also pushing for the separatist-held territories to be granted a large degree of autonomy, but Kiev only says that it is willing to decentralise some powers.
The bloodletting in eastern Ukraine has been relentless in recent weeks as the rebels have pushed deeper into government-held territory and Kiev forces have counter-attacked.
Separatists have been battling for weeks to take the rail hub of Debaltseve, while Ukrainian forces on Tuesday captured ground around the port city of Mariupol.