German Chancellor Angela Merkel and French President Francois Hollande are meeting Russia’s Vladimir Putin to try to end escalating fighting in Ukraine.
Meanwhile a truce has allowed civilians to leave Debaltseve, at the heart of the latest fighting in eastern Ukraine.
Russia is accused of arming pro-Russian separatists – a claim it denies.
The Kremlin also rejects claims by Ukraine and the West that its regular troops are fighting alongside the rebels in the eastern Donetsk and Luhansk regions.
Clashes have left nearly 5,400 people dead since April, the UN says.
A September ceasefire, signed in Minsk in Belarus, has failed to stop the violence. Since then the rebels have seized more ground, raising alarm in Kiev and among Ukraine’s backers.