Russia's railways expect to keep Yukos oil moving toward ports after today, when the firm's deadline to pay transport fees expires, a break for the oil company as it fights a potentially ruinous tax charge.

Yukos sources say its bank accounts have been drained and bailiffs say they are skimming any incoming revenues to cover $3.4 billion in back taxes demanded from the Russian oil giant.

But the state railway firm said yesterday it saw no shipping disruption after today.

"No supplies will be stopped after August 10. We will continue to work as we have been working in the past because it is in the state's interest," Marina Kovshova, head of Russian state railways' marketing department, told Reuters.

She said Yukos managed somehow to pay railway shipping fees beyond today, but declined to disclose details.

Yukos has said it paid only through Tuesday to ship some 300,000 barrels per day of oil to ports by rail, a scheme worked out long ago to bypass the crowded Transneft pipeline monopoly.

The potential payment gap raised concerns over supply problems from Russia that have helped to push oil prices up to around record high levels.

Yukos's troubles are seen by many as being orchestrated by the Kremlin to punish its main owner, Mikhail Khodorkovsky, for political ambitions. The jailed billionaire is now on trial on charges of fraud and tax evasion.

Transneft has said other producers could easily compensate for lost Yukos volumes if the oil giant was unable to pay its shipping fees. Yukos railway shipments are the main source of supply concern with crude oil trading community.

The major supplies up to 300,000 bpd by rail to the Arcticports of Vitino and Murmansk, Theodossia in Ukraine and China.

Other volumes bypassing Transneft go by river to the Black Sea port of Kavkaz.

On the Transneft front, Yukos, Russia's biggest oil exporter, is the major supplier of Poland, Slovakia, Hungary and Lithuania. The firm has said it had pre-paid fees to Transneft until the end of August.