Ukraine's president has laid the blame for the deaths of three policemen during a right wing demonstration on Monday firmly at the doors of the Kremlin, accusing Russia of extending its "campaign of destabilisation".

Three people died after grenades were thrown during clashes between nationalists and police outside Ukraine's parliament.

It followed a vote to give more powers to the regions, including separatist regions in the east.

Petro Poroshenko, a billionaire businessman who was elected in May last year at the height of a Russian campaign to seize the Crimea and back rebels in the east of Ukraine, said the killings were inspired by Moscow.

In an interview with Sky News, he insisted that his reform programme to bring his country closer to European Union norms and requirements was on track, notably tackling corruption and the planned lifting of immunity for politicians - including himself.

Part of his business empire was built on confectionery - as a result he is known as the "chocolate king".

But it is the tsar-like leadership of Vladimir Putin that he says is a threat not only to his country but to wider European and global security - pointing out that even the UK regularly has Russian military aircraft testing its air space.

He said that Russia had become "unpredictable" but he did not feel vulnerable, even though "this is one of the most difficult presidencies in the whole world".

Mr Poroshenko's comments come following reports that two people have been killed and six wounded near the city of Luhansk, following an ambush on a Ukrainian army vehicle.

BBC reports that it is the first major incident since a fresh truce between government forces and rebels.