The continued fighting in eastern Ukraine has made a mockery of the West's latest attempts to negotiate a ceasefire but may ultimately pave the way for a more durable peace, say analysts.

It did not take long for the latest truce, brokered by France and Germany and signed in the Belarussian capital Minsk last week, to look as impotent as previous deals.

Germany and France demanded Friday that a crumbling Ukraine truce be "fully respected" even as pro-Russian rebels celebrated a battlefield victory in a strategic town and exchanged artillery fire elsewhere with government troops.

"The ceasefire has been violated several times," French President Francois Hollande said in a joint Paris media conference with German Chancellor Angela Merkel.

EU head Donald Tusk said Friday he was consulting EU leaders on the next steps to take to increase "the costs of aggression" in eastern Ukraine where a ceasefire has failed to stop the fighting.

With the latest peace accord breached more than 300 times, "we are clearly reaching a point when further diplomatic efforts will be fruitless unless credibly backed up by further action," Tusk said in a statement.

Ukraine must pay for Russian gas being supplied to rebel areas in the country's war-torn east, Russian Prime Minister Dmitry Medvedev said Friday, raising the possibility of another gas dispute in the midst of winter.

Russian gas giant Gazprom began direct deliveries to separatist areas on Thursday in addition to other areas of Ukraine after Kiev temporarily cut supplies.

Burnt-out armored vehicles and crater-pocked plazas serve as grim reminders of the fierce battle for Debaltseve that ended with Ukrainian forces abandoning the strategic rail hub to pro-Russian troops this week.

In the center of the largely empty town the tail of an unexploded rocket stuck out of a road and homes were riddled with gaping holes after the fierce mortar fire.

A stream of sombre Ukrainians on Friday laid flowers at memorials on Kiev's Independence Square where one year ago scores of demonstrators were gunned down in the final act of a dramatic uprising. 

Some wept and others crossed themselves in silence in front of the pictures of some 100 protesters who died during the months of protests that eventually toppled Kremlin-backed president Viktor Yanukovych.

Britain and Spain said Thursday the solution to the Ukrainian conflict had to come through dialogue and should not involve military aid to Ukrainian forces.

"We do not believe that at the moment it would be helpful to provide lethal support to the Ukrainian armed forces," British Foreign Secretary Philip Hammond told a news conference with Spanish Foreign Minister Jose Manuel Garcia Margallo in Madrid.

Russia's Gazprom on Thursday started supplying gas directly to the rebel-controlled area in east Ukraine after pro-Moscow separatist leaders said Kiev had cut supplies, the company's chief said.

"From 1600 (1300 GMT) on February 19, Gazprom is supplying gas to Ukraine including through the Prokhorovka and Platovo gas metering stations to an amount of 12 million cubic meters per 24 hours," said Alexei Miller, quoted by RIA Novosti news agency.

The leaders of Ukraine, Germany, France and Russia on Thursday pledged to try to save a tattered ceasefire in eastern Ukraine despite violations -- including the storming of a key town by pro-Russian rebels.

As the leaders condemned the fighting and urged both sides to observe the truce, there was strident opposition from the separatists and Moscow to a plea from Ukraine for international peacekeepers to enforce the ceasefire.

Russia could inflict the tactics it is accused of using to destabilize Ukraine on Baltic members of NATO, Britain's defense minister warned in comments to British newspapers on Wednesday.

Michael Fallon said that NATO must be prepared for Russian aggression in any form, and warned of a "real and present danger" to Baltic members of NATO -- eurozone members Estonia, Latvia and Lithuania.