Ukraine’s interior minister has warned that force will be used against pro-Russian separatists holding government buildings in eastern Ukraine, if negotiations in the next 48 hours fail.

“There are two options – political and negotiations, and force,” the minister Arsen Avakov told journalists on the margins of a government meeting.

In Luhansk protesters have reinforced barricades and prepared petrol bombs at a security services building they seized.

Both sides say 50 people left the building overnight – and deny earlier reports that hostages were taken.

The stakes are high for Vitaly, the leader of the pro-Russian armed activists.

“This is out last chance. Kharkiv is lost, Donetsk is lost, (the southern town of) Mykolaiv has been lost long ago, Odessa is almost lost. That’s it, we are the last remaining hope of all Ukraine,” he said despondently.

Protesters in Donetsk, to the south, remain in control of one building – the main regional authority headquarters – but Ukrainian authorities have ended the occupation in Kharkiv.

Beyond the barricades, a wider geopolitical game is being played out.

Russia has again dismissed Western concerns over its forces on the Ukrainian border.

Kyiv and its allies have accused Moscow of orchestrating unrest – possibly to seize more territory.

“We expect to have freedom, we want our Donetsk republic to unite with everybody who wants to unite with us,” said one woman in favour of a breakaway from Ukraine.

“We want Donetsk to remain a Ukrainian city, we love it, we love our Ukraine,” said another.

Moscow has warned Kyiv that using force to end the separatist protests could lead to civil war.

It is boycotting a meeting of the Organisation for Security and Cooperation in Europe (OSCE) this week, accusing the US and Ukraine of using it to mount “an anti-Russian campaign”.