Russia started cutting off gas to its cash-strapped neighbors Ukraine and Belarus on Thursday because they have not paid for previous deliveries, raising the prospect of disruptions in supplies to Western Europe.Gennady Kremenskov, deputy head of Gazprom, said supplies to Ukraine and Belarus would gradually be cut back over a three-day period, then halted. "We will resume deliveries after an agreement on back payments is reached," he told The Associated Press.


Vladimir Podmarkov, chief engineer at Gazprom, said his company started reducing supplies to both countries from 10 A.M.


Podmarkov told The Moscow Times that Ukraine owed Russia 1 trillion rubles ($590 million) in back payments. But Volodimir Fyodorov, economic representative at the Ukrainian Embassy in Moscow, told Itar-Tass that the total debt was only 300 billion rubles. He said the conflict over payments erupted after the failure of a plan under which Ukraine would cover the debt by supplying 14 fishing boats to Russia.


Senior Ukrainian officials confirmed supplies had dropped sharply. "The pressure in the pipeline has fallen, but we don't know the exact figures yet," Vasily Rozgonyuk, chief engineer of state natural gas company Ukrgazprom, told AP. Another official described the cutoff as "a bomb exploding on Ukraine."


Gazprom said its customers in Western Europe would not be affected. But Ukrainian officials have warned that, in response to a cutoff, they could syphon gas from pipelines that cross Ukraine.


Virtually all of Russia's gas exports to the West pass through Ukraine, where close to freezing temperatures and heavy snow might increase the temptation to tap into pipelines.


Gazprom pumps 500 million cubic meters of gas a day to Ukraine, about half of which is for Ukraine The rest is mostly for Germany, France, Italy, the Czech Republic, Slovakia, Poland, Romania, Bulgaria and Hungary.


Big Western consumers, such as Germany's Ruhrgas AG, Gaz de France and Italy's Snam SpA, say they are not too concerned by the Ukrainian cutoff since they do not rely solely on Russia for supplies.


Russian gas was flowing normally to Austria's OMV AG Thursday. "The problems between Russia and Ukraine are a long-running saga. Supplies to Austria are continuing. Our storage facilities are full. No panic," Reuters quoted the OMV AG spokesman as saying.


Gazprom's Podmarkov said Ukraine had been syphoning off about 20 percent of gas meant for the West, or up to 40 million cubic meters a day, since Feb. 20 the day Ukraine's other supplier, Turkmenistan, cut off Kiev for nonpayment. Ukrainian officials deny the accusations.


On Wednesday, Ukrainian officials said they had agreed to pay Russia $20 million of its debt for natural gas before March 5, but the Russian firm spurned the offer, saying it was insignificant.


In Kiev, a senior gas official said the republic was receiving 40 million cubic meters less on Thursday than previously. "They could cut 30 million more," Tadey Mihailevych, chief dispatcher at Ukraine's gas company, said.


Gazprom said it had been delivering over 200 million cubic meters a day to Ukraine since Turkmenistan cut off deliveries.


In the Belarussian capital Minsk, a gas official said: "The pressure in the gas pipeline from Russia fell sharply this morning."


Belarussian officials said Minsk could not afford to pay its debt to Gazprom of 400 billion Russian rubles .


But in Moldova, another republic threatened with a cutoff, an industry official said the Russian firm had agreed to a barter deal involving exchanges of consumer goods and farm produce for gas.


The head of Moldova's gas company met Gazprom officials in Moscow on Wednesday after the Russian firm threatened to start cutting supplies because of debts for previous deliveries of about 53 billion rubles.