Pro-Russian militia continue to assault symbols of the Ukrainian state.

The latest attack saw a police station in Horlivka, near Donetsk, stormed by a crowd on Monday.

Video footage on Ukrainian television showed an ambulance treating people apparently injured in the attack. A resident who implied Moscow was orchestrating such attacks was punched and kicked by the rebels.

By the afternoon, about 150 people stood outside the station, some donating money to men in masks and camouflage fatigues for supplies, as others brought tyres to fortify barricades.

The assault at Horlivka happened after Ukraine’s interim president issued an ultimatum to pro-Russian supporters to disarm and leave government buildings.

Olexandr Turchynov insisted on Monday that the military offensive would go ahead.

But in a sign of discord behind the scenes, the state security chief has been sacked.

Pro-Russian protesters have seized government buildings in some 10 eastern Ukrainian cities, in the Donetsk and Luhansk regions – in a major challenge to Kyiv’s authority.

They want local referendums to join the Russian Federation or at least obtain more local autonomy.

Ukraine’s government in Kyiv suspects Moscow has been directly involved in attacks on government buildings, saying it has proof that Moscow is mounting a campaign of agitation.

Rebels, it says, are armed with weapons used only by Russian military forces.

Russia says the armed men are all locals acting on their own, but reserves the right to intervene to protect them.