Pro-Russian activists in eastern Ukraine flouted a Kiev deadline to clear out of government buildings today, with a crowd taking control of another police station.

Activists stormed a station in Horlivka, near Donetsk, in the early hours of this morning.

Armed men in masks also seized control of an airport in the same region later in the day.

Hapless interim President Olexander Turchynov did not repeat earlier threats to send in troops, instead saying his administration was “not against” holding referendums on greater independence.

He suggested that a vote on greater federalism could be held alongside presidential polls on May 25.

But he did ask UN secretary-general Ban Ki Moon to bring in peacekeepers for an “anti-terrorist operation” with Ukrainian forces.

Such a force would require authorisation from the UN security council, where Russia holds a veto.

Russian presidential spokesman Dmitry Peskov said earlier today that Vladimir Putin had received “numerous appeals” from eastern Ukraine “asking him to help and interfere in one way or another.”

Mr Putin was “watching the developments in those regions with great concern,” he added.

A US military official claimed yesterday that a Russian fighter plane made multiple close-range passes of a US destroyer in the Black Sea on Saturday.

The anonymous official said a Russian Su-24 Fencer flew within 1,000 yards of the USS Donald Cook, which ship commanders considered provocative and inconsistent with international agreements.

The aircraft was unarmed and never posed a threat, said the official.

That came a day before the UN security council met to discuss the situation.

Washington again accused Russia of being behind the well-orchestrated seizure of government buildings.

“These armed units … raised Russian and separatist flags over seized buildings and have called for referendums and union with Russia,” said US ambassador Samantha Power.

“We know who is behind this.”

Russian ambassador Vitaly Churkin made a denial and accused Ukraine’s coup-installed government of “waging a war against its own people.”

“Some people, including in this chamber, do not want to see the real reasons for what is happening in Ukraine and are constantly seeing the hand of Moscow in what is going on,” he said.

“Enough. That is enough.”