BRATISLAVA: Slovakia said Monday that Russia had warned it might halt oil supplies through Ukraine to three European Union countries over a price dispute.

Quoting a letter from the European Commission -- the 27-nation EU's executive arm -- the Slovak government said Russia had announced "the possibility of suspending oil supplies to... Slovakia, Hungary and the Czech Republic."

"The reason is allegedly unresolved problems between the Russian Federation and Ukraine concerning oil transit," the government said.

A spokesman for Ukraine's state oil pipeline operator Ukrtransnafta told AFP that Ukraine wanted to modify the current contract under which its transits Russian oil shipments to Europe.

Slovak Prime Minister Robert Fico told journalists that Ukraine was asking higher fees for oil transit from Russia, and that talks between Moscow and Kiev were "very complicated."

"The risk that oil supplies may be suspended as of January 1 if no agreement is reached has increased remarkably," Fico said, adding however that a stoppage would not be a problem as Slovakia has "oil and oil products for a period longer than 94 days."

In the Czech Republic, meanwhile, Deputy Industry Minister Tomas Huener said his country's reserves of oil and related products would also last more than 90 days.

"We also have alternative routes," Huener told Radio Cesko, notably the IKL pipeline which brings Caspian, Middle Eastern and North African oil from the Italian port of Trieste.

An EU source said Brussels was monitoring the situation and that there was no immediate cause for alarm.

"We are not talking about a repeat of the situation that caused so many problems for citizens and businesses a year ago," the source said on condition of anonymity.

In January 2009, Russia halted gas supplies via Ukraine over a price dispute for several days, leaving swathes of the EU without heating amid a severe winter.