Talks involving France, Germany and Russia aimed at resolving the Ukraine crisis have ended without any word of an agreement.
German chancellor Angela Merkel, French president Francois Hollande and Russian president Vladimir Putin met in Moscow for more than five hours to discuss the situation, which has flared up in recent days.
Kremlin spokesman Dmitry Peskov said the leaders had agreed at “constructive talks” to continue working towards a possible joint document on implementing a ceasefire agreement reached in the Belarussian capital Minsk last September.
The three leaders’ next contact, he said, was expected to be by phone on Sunday.
In a sign of the tense atmosphere, Dr Merkel and Mr Hollande went straight into the Kremlin for talks after arriving in Moscow, without the usual diplomatic niceties of a welcoming handshake for the cameras.
They emerged briefly after a 75 minute working dinner for a photo opportunity in an ornate Kremlin hall, before talks resumed.
Their visit follows fierce fighting and territorial gains in eastern Ukraine by Russian-backed separatists since a peace blueprint was agreed in Belarus in September.
Five hours of late-night talks involving Dr Merkel, Mr Hollande and Ukrainian leader Petro Poroshenko were held in snow-bound Kiev on Thursday.
Back in their respective capitals in between the meetings, Mr Hollande called the talks “the first step”, while Dr Merkel said it was unclear whether the meeting in Moscow would secure a ceasefire.
Their initiative follows fierce fighting and territorial gains in eastern Ukraine by Russian-backed separatists since a peace blueprint was agreed in Belarus in September.
The conflict has killed more than 5,000 people and the Ukrainian military reported that two more soldiers had been killed in the past 24 hours in the east, with 26 wounded.
The growing military pressure has shaken the Ukrainian economy and driven a debate over the possibility of the United States providing Kiev's hard-pressed army with arms.
Dr Merkel said she and Mr Hollande were not on the road as neutral mediators but were representing European interests. “These interests are peace, maintaining Europe’s peaceful order.”
A statement on Mr Poroshenko’s website said the sides had expressed the hope that “Russia had an interest in” a peaceful settlement of the conflict.
For Moscow's part, Russia's ambassador to France Alexander Orlov told Europe 1 radio there was an urgent need to avoid war. "I wouldn't say it's a last chance meeting, but it's not far off," he said.
The Ukrainian presidential statement said he and the German, and French leaders had called for a quick ceasefire, the withdrawal of foreign forces from Ukraine, the pull-back of heavy weapons and equipment, the closure of the border and the release of all prisoners.
The major powers were due to come together again on the Ukraine crisis at an international security conference in Munich, Germany, at the weekend.
In Brussels, en route for Munich, US vice president Joe Biden said the United States and Europe had to stand together over Ukraine and accused Mr Putin of calling for peace while rolling his troops through Ukrainian countryside.
"This is a moment where the United States and Europe must stand together, stand firm. Russia cannot be allowed to redraw the map of Europe because that's exactly what they are doing," Biden said as he arrived for a meeting with European Council President Donald Tusk.
He made no mention of possible US arms supplies to Ukraine to fight separatists in the east of the country, which some European leaders fear would merely escalate the conflict.
In Kiev, Ukrainian prime minister Arseny Yatseniuk made an undisguised pitch for military help from the West. "Nobody wants a full-scale war in Europe, but I am convinced nobody in Europe wants to see Russian tanks on the borders of the EU," he said at a briefing with the visiting Slovak prime minister.
“Peace in Europe depends on peace in Ukraine and for us to achieve that peace Ukraine must have the means to defend itself. Not in offensive operations, but in defence operations.”
On the ground, the rebels are advancing on a railway hub held by Ukrainian troops, who are almost encircled.
A collapse in Ukraine’s hryvnia currency further highlighted the importance of reaching a deal. It lost nearly a third of its value on Thursday after the central bank halted daily auctions at which it sold hard currency to banks.
Though details of the peace deal were under wraps, much might depend on whether Ukraine is being pressed to acknowledge existing front lines as the new negotiating reality - and whether Kiev would accept this.
German government sources said on Thursday the key problem for resuming peace talks was that current front lines no longer tally with what was agreed at talks in Minsk, Belarus, last year.
One idea was that a new attempt at a ceasefire should take in the current front lines, which reflect rebel gains, without Kiev having to give up its claim to these areas as part of the Ukrainian state.