Sergei Lavrov
Russia's Foreign Minister Sergei Lavrov speaks during a meeting with his Slovak counterpart Miroslav Lajcak in MoscowReuters

Russia has opened the door to European Union proposals to reverse gas flows from Slovakia to Ukraine after the Russian foreign minister said the move would not violate agreements with Russia.

"We have no complaints over that," Sergei Lavrov told journalists at a joint press conference with his Slovak counterpart.

Ukraine has been scrambling for alternative energy sources after Russia almost doubled the price it charges Ukraine for gas and demanded immediate payment of outstanding bills for $3.51bn. Ukraine said the new price of $485 per 1,000 cubic metres was "political" and refused to pay.

Kiev has recently been trying to arrange more gas purchases from Europe after Russia's state-owned energy giant Gazprom threatened to cut off gas deliveries if Kiev did not settle its outstanding bills.

Russia has previously cut off gas supplies to Ukraine on two occasions over price disputes in 2006 and 2008. Ukraine and some European countries experienced supply shortages as a result and Russian president Vladimir Putin warned European leaders this month that they could be affected if Gazprom cuts deliveries to Ukraine.

Meanwhile, the European Union's Energy Minister Guenther Oettinger has announced two fresh rounds of talks will take place between the EU, Russia and Ukraine before the end of the month.

"We have a timeframe that ends on June 1. We want to do all we can in two rounds of talks next week to clear up the open questions," he told German television channel ARD.

"Next Monday the next round of talks with the EU, Russia and Ukraine are planned," he added.

Oettinger said the EU was hoping to act as a mediator in the talks aimed at reducing the price Kiev pays for gas.

"We want to negotiate a market price for Ukraine so that it is in a better position than it would be with the demands Mr Putin has been making since April 1," said Oettinger.

"Somewhere in the middle would seem to be a fair result of negotiations," he stressed.

Ukraine relies on Russia for around half of its gas needs and the country is a crucial transit route for Russian gas exported to Europe via its pipelines. The European Union receives a third of its total gas from Russia, around half of which arrives via Ukraine.

The Kremlin also confirmed Russian President Vladimir Putin had ordered Russian troops to withdraw from areas close to the Ukraine border.

However, Putin has made similar announcements before without actually withdrawing Russian forces. NATO chief Anders Fogh Rasmussen said he had not seen evidence of any withdrawal so far.