Sofia - Hit hard by the Russia-Ukraine gas row, Bulgaria on Tuesday stepped up the pressure for permission to re-start its old nuclear reactors, shut down in 2006 amid European safety concerns.

"We must prepare without delay to re-start the third reactor at Kosloduy," President Georgi Parvanov said. Bulgaria shut down two 440-megawatt, Soviet-era reactors shortly before it joined the European Union in 2007, meeting Brussels' demands.

Two even older reactors were turned off in 2002.

Parvanov said the accession contract with the EU allows Bulgaria to revive the two newer reactors in case of a crisis.

"I hope our European partners will not oppose our demands," he said.

Bulgaria faces a serious energy crisis since Russia turned off the gas taps to Ukraine, which it accuses of stealing gas.

Along with Macedonia, Greece and Turkey, Bulgaria was cut off as collateral damage in the row and now has only about a third of the 12 million cubic metres of gas it normally uses on a winter day.

Kosloduy engineers, who now operate two modern, Russian-built 1,000-megawatt reactors, could bring one of the two older reactors online within a month, the power plant chief executive Ivan Genov said. (dpa)