Bulgaria was preparing contingency plans to ration gas to industrial consumers in case the country faced a repeat of the January gas crisis, Economy Minister Petar Dimitrov said on March 4.

Relying entirely on Russian gas transited through Ukraine, Bulgaria was hit the worst when the pricing dispute between Moscow and Kiev led to a complete halt to all deliveries through Ukrainian pipelines.

Ukraine's state-owned oil and gas company Naftogaz is yet to pay the full bill for February gas deliveries, which could prompt Gazprom to cut off deliveries again.

"There are no grounds to believe that the crisis is inevitable," Dimitrov was quoted as saying by Dnevnik daily, but conceded that the most likely outcome was a reduction in the amounts of gas shipped through Ukraine.

Naftogaz said that it has paid 80 per cent of the bill and the rest would be transferred by the March 7 deadline, Reuters reported. But after Ukraine's security service raided Naftogaz headquarters on March 4 as part of a criminal investigation into the company, gave rise to fears that Naftogaz' ability to make the payment could be disrupted.

The raid, carried out by armed officers of an agency directly overseen by president Viktor Yushchenko adds a new twist to the power struggle between the president and prime minster Yulia Tymoshenko, close allies during the 2004 "orange revolution", who have since become bitter rivals.

Bulgaria has been pumping gas into its Chiren gas storage to prepare for any possible shortfall in deliveries, an unprecedented move during winter months, Dimitrov said. In case deliveries were interrupted, Bulgaria could also pump gas from Greece and Turkey, with whom Bulgaria reached agreements to that end during the January gas crisis, he said.