Ukraine's leading English-language newspaper since 1995

Slovakia delayed on Tuesday a decision on restarting a Soviet-era nuclear reactor amid gas shortages, a move that would have put it on a collision course with the European Union which is critical of the plan.

Bratislava declared a state of emergency after the flow of Russian gas stopped last week, which had cut supplies to major industries and gas-powered electricity facilities.

The government said the Jaslovske Bohunice reactor, viewed by neighbouring Austria as unsafe, had to be put into operation again to maintain power supplies.

But Prime Minister Robert Fico said on Tuesday Slovakia had secured back-up generating capacity and possible imports to keep power running for now.

"Some extraordinary measures were taken last night, which means we are able to maintain stability of the electricity system for several more days," Fico told a news conference.

"But, at the same time, I have to say the possibility of restarting (the nuclear unit) is still very relevant... All preparatory works have been completed, we are prepared on the technical level," he said.

Slovakia reluctantly shut down a unit of the Jaslovske Bohunice power station at the end of last year, meeting an obligation made to the EU before it joined the bloc in 2004.

The European Commission warned Slovakia not to reopen the plant, saying the move would prompt legal action from the European Union's executive arm.

"The decision to reopen temporarily the operations of the second unit of the nuclear plant is in contradiction with the obligation of the Slovak Republic following the (EU) accession treaty," a Commission spokesman told a daily briefing.

"Commission services already started preparations for a college decision to launch an infringement procedure."

A European court may order fines in such procedures.

Fico had opposed the accession deal, agreed by the previous centre-right administration his government replaced two years ago, and has repeatedly said the Bohunice unit meets all safety standards.

He has, however, taken a lighter approach to restarting the reactor, compared with statements made over the weekend when he said the unit would be connected to the grid until gas supplies were stabilised and gas storages were full again.

The leftist leader said on Tuesday Slovakia wanted to "minimise damage" that could be caused by restarting the unit.

The gas dispute, which began when Russia and Ukraine could not agree on the price Ukraine should pay for Russian gas this year, has intensified calls for alternative energy sources.

Slovakia's southern neighbour, Hungary, has said it needs to consider whether to build new nuclear power generating capacity.

Bulgaria, among the hardest-hit by the gas supply cuts, also said it might be forced to restart a nuclear power reactor shut down in 2006 as part of its EU accession deal if the cut-off in gas deliveries dragged on. (Additional reporting by Marcin Grajewski in Brussels and Anna Mudeva in Sofia, writing by Jan Lopatka and Peter Laca)