Ukraine, rebels withdraw 'lion's share' of weapons: Poroshenko

Kiev (AFP) - Both sides in the conflict in eastern Ukraine have withdrawn most of their heavy weapons from the frontline, bolstering a month-old truce, Ukrainian President Petro Poroshenko has said.

In an interview with state television Monday evening Poroshenko said government forces had "withdrawn the lion's share of multiple launch rocket systems and heavy artillery."

"We see that the Russian-backed militants have also withdrawn a significant part," he added.

Poroshenko confirmed that the ceasefire deal hammered out by France, Germany, Russia and Ukraine in the Belarussian capital Minsk on February 12 was largely holding, despite sporadic deadly clashes.

Artillery fire had halted among most of the 485-kilometre frontline, after Kiev "managed to stop the aggressors," he said.

But the army was still sustaining losses in some flashpoints, with 64 soldiers killed since the peace deal came into effect on February 15, bringing to 1,549 the number killed since the war started, he said.

However, Kiev's forces sustained around a third of the fatalities when separatists forced them out of the transport hub of Debaltseve three days into the truce.

- Russia 'undermining' East Europe -

Since then the fighting has considerably abated, with both sides making a show of towing away rocket launchers and other big guns used in the 11 months of fighting that has killed over 6,000 people.

The separatists rarely announce their own casualty figures.

Ukraine and the West accuse Russia of providing separatists with troops, training and weaponry. Moscow denies this, but despite the lull has remained under strong diplomatic pressure from European capitals and Washington.

British Foreign Secretary Philip Hammond on Tuesday accused President Vladimir Putin of undermining other former Soviet republics, besides Ukraine.

- Rebels demand negotiations -

"We are now faced with a Russian leader bent not on joining the international rules-based system which keeps the peace between nations, but on subverting it," Hammond told the Royal United Services Institute (RUSI) in London.

"President Putin's actions -- illegally annexing Crimea and now using Russian troops to destabilise eastern Ukraine -- fundamentally undermine the security of sovereign nations in Eastern Europe," he said as NATO forces prepared for a major exercise in the Baltic states.

US military officials said that deployment of some 3,000 troops had begun for the three-month Operation Atlantic Resolve. The exercise will see NATO forces working alongside their allies in Estonia, Latvia and Lithuania.

The United States also said Monday that it had delivered more than 100 pieces of heavy military equipment to the Baltic states.

The uneasy calm in eastern Ukraine has been riven with mutual accusations of repeated ceasefire violations.

On Monday, the Ukrainian army accused the separatists of using mortars and a tank to fire on government positions near the eastern port of Mariupol.

The clashes lasted all day. Nine Ukrainian soldiers were injured but held their positions, security spokesman Andriy Lysenko said Tuesday.

Western leaders have warned that any attempt by the rebels to seize the city of 500,000 would trigger further sanctions against Russia.

While denying meddling in eastern Ukraine Putin has acknowledged ordering the annexation of Crimea from Ukraine a year ago, sparking the worst crisis in East-West relations since the Cold War.

The rebels who took up arms against Kiev's pro-Western government days after the Crimea annexation insist they are upholding their end of the Minsk agreement.

An official with the Donetsk People's Republic , one of two self-proclaimed rebel entities, accused Kiev Monday of reneging on its end of the deal.

"Kiev has not conducted a proper withdrawal of heavy arms," Andrey Purgin, speaker of the republic's People's Council, told Interfax news agency.

"Everything is gradually going back to the way it was," he said, calling for Kiev to enter talks on the future political status of the rebel-held areas.