Ukraine’s acting prime minister is travelling to the east of the country to try to end a stand off with pro-Russia protesters.
Arseniy Yatsenyuk will visit the city of Donetsk, where activists have declared a “people’s republic”.
He will meet local leaders, including the governor of the Donetsk region and the mayor of the city.
The trip comes amid rising tension between Russia and the US over Russian gas supplies and troop movements.
Nato says up to 40,000 Russian troops are massed near Ukraine’s border.
Energy ultimatum
A spokesperson for Mr Yatsenyuk said he was expected to discuss transferring some powers to Ukraine’s regions.
Mr Yatsenyuk is also expected to travel to another eastern city, Dnipropetrovsk, which has also seen protests.
As well as the local government building seized in Donetsk, activists in Ukraine’s mostly Russian-speaking east are occupying a government building in the city of Luhansk.
Ukrainian officials are trying to negotiate a deal whereby the protestors would vacate the buildings in return for protection from prosecution.
Interior Minister Arsen Avakov had on Wednesday said he expected the situation in the east to be brought under control within 48 hours, by “negotiations or force”.
Kiev accuses Russia of orchestrating the unrest, as a provocation similar to the protests that gripped Crimea days before Russian troops annexed the peninsula last month. Russia denies the claim.
On Thursday, Russia’s President Vladimir Putin said gas supplies to Ukraine could be cut if Kiev did not pay off its debts, and warned this could affect gas deliveries to Europe.
Russian energy giant Gazprom says Ukraine owes it $2.2bn (£1.2bn; 1.4bn euros) and recently doubled the price it must pay.
In a letter to 18 European countries Mr Putin said that if Ukraine did not settle its energy bill, Gazprom would switch to advance payment, and if those payments were not made, it would “completely or partially cease gas deliveries”.
Previous Russian gas disputes with Ukraine have led to gas shortages in several European Union countries. The EU says it has extra supplies to deal with any such disruption now.
The US has accused Russia of using its energy supplies “as a tool of coercion” over Ukraine, and said it was working to help Ukraine find gas and financing.
President Barack Obama told German Chancellor Angela Merkel that the US and its allies should prepare for fresh sanctions against Russia if the crisis escalates.
In a telephone call on Thursday, they discussed the talks due to take place in Geneva next week between Russia, Ukraine, US and the EU – the first four-way discussions since the crisis began.
Ukraine’s crisis began in November when Ukraine’s former President Viktor Yanukovych – an ally of Russia – refused to sign a far-reaching partnership treaty with the EU. That triggered huge anti-Yanukovych demonstrations and violence which led to him fleeing to Russia in February.
Russia later annexed the mostly ethnic Russian Crimea region following a referendum that approved joining the Russian Federation.
Separately, Nato has defended the accuracy of satellite images which it says show Russian troops massed on the Ukrainian border in recent weeks.
A Russian official earlier said the images depicted a military exercise that was held in August last year.
Nato says the satellite images it unveiled early on Thursday show some 40,000 Russian troops near the border in late March and early April. They also reveal sophisticated warplanes and helicopters.
Later, Nato released additional images, some dating back to 2013 and others from early 2014, purporting to show the same areas unoccupied prior to March.
In a statement, the alliance says the images show that Russian claims that they are old were “categorically false” and that there was no evidence of military activity in these areas in 2013 or early 2014.
Source: BBC