Pro-Russian supporters have rallied in Donetsk just hours before Crimea decides if it wants to join Russia or not in a referendum.

Tension and security in the city, like elsewhere in eastern Ukraine remains high, after deadly overnight clashes in the east’s other main city Kharkiv.

In the capital Kyiv, Ukraine’s acting president Oleksander Turchinov slammed Russia, accusing ‘Kremlin agents’ of fomenting deadly violence.

‘‘There is one law for everybody. Those who try to de-stabilise the situation, try to capture buildings, try to act in ways which violate the constitution and the law of the land, these agents work for those trying to annex Ukraine. They are working for the enemies of the Ukrainian people,’‘ Turchinov said.

The president’s claim of Kremlin-orchestrated violence came after the killings of two men in Kharkiv on Friday.

Several other activists were also badly wounded in the shootout.

Kyiv has said it fears Moscow is stirring up unrest to provide a pretext to invade, claiming Russia has massed thousands of troops along Ukraine’s border.

The Kremlin has denied any invasion plan exists.