The leaders of Germany and France announced a new peace plan for Ukraine on Thursday, flying to Kiev with a proposal they would then take on to Moscow.

The leaders of Germany and France announced a new peace plan for Ukraine on Thursday, flying to Kiev with a proposal they would then take on to Moscow.

The coordinated trip by Chancellor Angela Merkel and President Francois Hollande comes as separatists advanced on a railway hub held by Ukrainian troops after launching an offensive that violated a five-month-old ceasefire.

With Washington moving towards a decision soon on arming Ukraine, US Secretary of State John Kerry also visited Kiev on Thursday. He had no plans to go to Moscow and was not involved in the Franco-German initiative, although he supported it.

Moscow said it hoped talks with Merkel and Hollande would be "constructive".

"Together with Angela Merkel we have decided to take a new initiative," Hollande told a news conference. "We will make a new proposal to solve the conflict which will be based on Ukraine's territorial integrity."

He and Merkel met President Petro Poroshenko in Kiev on Thursday and were expected to go to Moscow to see Russia's Vladimir Putin on Friday.

Poroshenko said the talks "gave hope that there will be a result in a ceasefire", his office said in a statement.

Hollande said earlier: "For several days Angela Merkel and I have worked on a text ... a text that can be acceptable to all."

Ukrainian Prime Minister Arseny Yatseniuk said Kiev would not consider any peace plan that casts doubt on the nation's territorial integrity, sovereignty or independence.

The Franco-German plan looks like an eleventh-hour bid to halt the escalation of the conflict ahead of diplomatic deadlines likely to make east-west confrontation even worse.

Peace talks collapsed on Saturday in Belarus and EU leaders are expected to consider new sanctions against Moscow next week.

NATO accuses Russia of sending weapons, funds and troops to assist the rebel advance, negating a ceasefire in eastern Ukraine where conflict has already killed more than 5,000.

Moscow denies involvement in fighting for territory the Kremlin now calls "New Russia".