The United States and Germany have challenged Russia over the apparent involvement of its military in eastern Ukraine, as pro-Moscow rebels made rapid gains in clashes with government forces in the region.
Just hours after the Ukrainian and Russian presidents met and pledged to seek a peaceful resolution to the bloody crisis, Kiev and western allies questioned whether Moscow’s troops were fighting alongside separatist militants.
German chancellor Angela Merkel spoke by telephone to Kremlin leader Vladimir Putin last night and "emphasised Russia's major responsibility for de-escalation and watching over its own frontiers".
“The latest reports of the presence of Russian soldiers on Ukrainian territory must be explained,” said her spokesman Steffen Seibert.
In Washington, state department spokeswoman Jen Psaki said “these incursions indicate a Russian-directed counter-offensive is likely underway in Donetsk and Luhansk” regions.
In Kiev, meanwhile, Ukraine’s security services said they had captured a Russian soldier who admitted his unit had funnelled heavy weapons to the rebels.
As well as continuing to shell Ukrainian positions, Russian troops crossed the border with armoured vehicles and established a tactical base about 60km from the major city of Donetsk, according to Kiev's military spokesman, Andriy Lysenko.
He said Russian forces had entered several other villages in Donetsk region, and that fierce fighting was taking place around Novoazovsk, a town on the Azov Sea between the Russian border and the major port of Mariupol. It was not clear who controlled Novoazovsk last night, but its loss would be a blow to government forces that fear the Moscow-backed rebels want to secure a strip of land linking Russia with the Crimean peninsula annexed by the Kremlin in March. This new front in fighting could give the insurgents access to the sea.
Senior Ukrainian interior ministry official Viktor Chalavan said government forces were surrounded in the town of Ilovaisk, which has been the centre of heavy fighting for several days, due to the arrival of Russian forces.
"No one can take seriously talk of separatists in Ukraine at this point," said Poland's prime minister Donald Tusk.
“There is information, which in the last few hours has received additional hard confirmation, that regular Russian units are operating in eastern Ukraine.
“This Nato information — that has also been confirmed by our intelligence service — is now practically unambiguous.”
Nato and the United States have openly accused Moscow of supplying fighters and high-tech weapons to Ukraine’s insurgents, and alleged that they accidentally shot down a Malaysian airliner last month with a Russian missile.
The European Union has taken a less confrontational tack with Russia - fearing a damaging trade dispute and energy-supply problems - and is pressing Ukraine to make concessions that would mollify the Kremlin.
But it is becoming increasingly difficult for EU states that want to maintain cordial relations with Russia – foremost among them Germany – to ignore mounting evidence that Moscow’s military is active in eastern Ukraine, just as it was in Crimea.
Russia is also struggling to preserve the façade, claiming that 10 paratroopers captured in eastern Ukraine crossed the border “by accident”, and imposing a state media blackout on the funerals of soldiers reportedly killed there.
A group of Russian soldiers' mothers said yesterday it believed that some 400 servicemen had been been killed or injured in Ukraine, and the mothers of the troops held by Kiev's forces made a video appeal for their release. After talks on Tuesday in Belarus with Ukrainian president Petro Poroshenko, Mr Putin insisted Russia was not involved in the conflict and could only "help to create an atmosphere of trust" for talks between Kiev and the rebels.
