The acting president of Ukraine promised on Thursday not to prosecute pro-Russian militants occupying government buildings in the east of the country if they lay down their arms and end the four-day standoff.

The olive branch came as the clock ticked down to a Friday morning deadline for the separatists to walk out of the state security building in the eastern city of Lugansk and the seat of government in nearby Donetsk or face the possible use of force.

Acting President Oleksandr Turchynov told lawmakers that Ukraine's latest secessionist crisis could be resolved peacefully.

"If people lay down their arms and free the administration buildings ... we guarantee that we will not launch any criminal proceedings against them," he promised.

"We can solve this problem today," said Turchynov.

The militants holed up inside the Donetsk government seat were busy fortifying their barricades with razor wire and old tyres that could be set on fire in case of a police assault.

The pro-Russia militants' demands have added extra urgency to the first round of direct talks that EU and US diplomats have managed to convince both Moscow and Kiev to join at the end of next week.

Moscow also slammed NATO's "double standards" Thursday as it took the roles of a referee and a court-marshal in Kosovo and Libya, while turning a blind eye to extremist forces in Ukraine.

Russian foreign ministry said in a statement that it was not surprised by NATO's attempt to represent itself as an "elite club" bearing some special political legitimacy and ignoring international institutions, including the UN Security Council.

Earlier this month, NATO suspend all civilian and military cooperation with Russia due to the crisis.

Russian lawmakers at the Council of Europe's parliamentary assembly Thursday were stripped of their voting rights until the end of 2014.

The Russian lawmakers boycotted the debate over the resolution, describing it as a "farce."