EU candidate Bulgaria agreed last week to close reactors three and four of its only Soviet-era Kozloduy nuclear plant by 2006. Brussels says the reactors cannot be made to meet safety standards at a reasonable cost.

Cabinet ministers say a refusal to comply with Brussels' demands would have hurt the Balkan state's foremost goal of completing EU entry negotiations next year and joining in 2007.

Closure of the reactors is a sensitive issue in Bulgaria, a leading regional power producer. The plant generates more than 40 percent of the country's electricity and any shutdown is likely to raise power prices for impoverished Bulgarians.

Sofia agreed in 1999 to close Kozloduy's first two units this year. The more modern reactors five and six will stay open.

Bulgaria's opposition centre-right Union of Democratic Forces and Socialist parties had accused the government of betrayal and violating the constitution.

Saxe-Coburg, the former king who took over the premiership in July 2001, rejected the accusations.

"Bulgaria will keep on being an energy leader in the region not only with Kozloduy but with (a second nuclear power plant in) Belene as well," he told parliament after the two votes.

Bulgaria said earlier this year it planned to resume building the Belene plant and was in talks with Canadian, Russian and U.S. companies, trying to secure the investment of $2 billion needed to finish the job.

The building of the Soviet-designed Belene started in the 1980s but idled due to lack of cash and environmental protests.

Opposition parties had previously signalled they would not make waves before last week's NATO summit in Prague to avoid damaging Bulgaria's chances of becoming a NATO member. Bulgaria was one of seven ex-communist states invited to join the pact.