Russian gas supplies delivered via Ukraine but destined for Bulgaria, Turkey, Greece and Macedonia have been cut off after Moscow accused Kiev of illegally siphoning off fuel.

Supplies to southeast Europe ground to a halt overnight on Monday, the Bulgarian ministry for the economy and energy said on Tuesday.

"Deliveries of natural gas at the Bulgarian-Romanian frontier from Bulgargaz, destined for the Bulgarian market and for onward transit towards Greece, Turkey and Macedonia were stopped at 01:30 GMT," a government statement said.

The ministry, which described the suspension of supplies as "a crisis situation", has convened an emergency meeting to address industrial safety concerns.

Naftogaz, Ukraine's state energy company, said Gazprom, Russia's state gas firm, had cut gas supplies to Europe by around two-thirds.

Speaking to Al Jazeera, Alexander Medvedev, the deputy chief executive of Gazprom, said Kiev had "aggravated" the situation by shutting down three or four export pipelines overnight.

He said the company was a "hostage of irresponsible behaviour".

Distribution hub

OMV, an Austrian energy company, said deliveries of Russian gas to Austria have dropped by 90 per cent.

"At the moment only around ten per cent of Russia gas is being delivered," OMV said in a statement on Tuesday.

Austria is a distribution hub which directs Russian gas to Germany and central Europe.

Officials in Croatia, Macedonia, which receive their natural gas through pipelines from Austria, confirmed that deliveries had ceased completely, while Slovakia said it was prepared to declare a state of emergency after its supplies were cut by 70 per cent.

"Gas supplies to selected wholesale buyers may fall, but we will do our best to spare households, hospitals and schools," Lubomir Jahnatek, the Slovakian economy minister said.

Hungary has announced that its Russian gas deliveries have ceased [AFP]

William Powell, the editor of International Gas Report, told Al Jazeera that reliance on Russian gas is greater the farther east you go in Europe.

"That's because Germany, Italy, France and so on, at the times of the Cold War, when they did these contracts with Gazprom, they were careful to limit the reliance on Russian gas to maybe 30 per cent or so of the total gas consumption."

"If you're Bulgaria though with no gas of your own, and trading with Russia on a barter basis then you would receive gas from Russia for almost free and you would exchange with them various products of your own manufacture," Powell said.

Ukrainian supply cut

Gazprom stopped deliveries to Ukraine after failing to resolve a $2bn debt dispute over payments owed to Russia and proposed increases to future fuel tariffs.

Naftogaz denies siphoning off gas, in a dispute that threatens supplies to Europe as a whole.

The latest development comes as members of the European Union commission are set to meet senior Ukrainian officials on Tuesday to discuss the crisis.

Europe, where temperatures have fallen below freezing, gets about 20 per cent of its gas via pipelines through Ukraine.

While concern over security of energy supplies have been mounting in Europe, analysts believe enough gas has been stockpiled to manage without Russia's supply for several days.