Ukraine's interim prime minister is meeting regional leaders in the east of the country on a mission to end a stand-off with pro-Russia protesters.Arseniy Yatsenyuk urged them to tell locals that the Kiev government would ensure security and economic progress in the east, Interfax news agency said.He is in Donetsk, where armed pro-Russia activists demanding self-rule are holding a government building.Separately, near the city, seven miners died in a gas explosion on Friday.Mr Yatsenyuk's trip comes amid rising tension between Russia and the US over Russian gas supplies and troop movements.Ukraine depends on Russian gas, but there is a dispute over alleged unpaid bills.Nato says up to 40,000 Russian troops are massed near Ukraine's border.In a statement on the crisis on Friday, Russia's Foreign Minister Sergei Lavrov called for legal guarantees of Ukraine's neutrality, reminding Nato that it should not try to draw Ukraine into the alliance.Energy ultimatumMr Yatsenyuk is expected to discuss transferring some powers to Ukraine's regions, his spokesman said.But Kiev is opposed to local referendums of the kind held in Crimea last month, after the peninsula was seized by pro-Russian troops.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 state security building in the city of Luhansk.Ukrainian officials are trying to negotiate a deal whereby the protesters 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".The interim government accuses Russia of orchestrating the unrest, as a provocation similar to the anti-Kiev protests which gripped Crimea. 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.Talks are due to take place in Geneva next week between Russia, Ukraine, US and the EU - the first four-way discussions since the crisis began.Last November 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.Troop movementsSeparately, 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.(BBC)ANN.Az