Russian oil major Yukos said on Sunday it had suspended oil exports by rail to China in the first sign of export disruptions due to its financial difficulties.
A Yukos spokesman said the company board had decided last week to suspend indefinitely shipments of crude oil to China by rail, which usually amount to 100,000 barrels per day (bpd).
"The Yukos board has decided ... to suspend all oil rail deliveries to China due to problems we are facing in paying our export duties and railway fees because our bank accounts are frozen," he said.
Yukos is Russia's largest exporters, sending around a million barrels per day to Western markets and China.
The company has repeatedly said it may be forced to cut production and exports after bailiffs froze its bank accounts as part of efforts to recover more than $7 billion in back taxes from the company for 2000-2001.
Yukos's tax troubles are part of a broader campaign seen by analysts as orchestrated by the Kremlin to punish its founder, Mikhail Khodorkovsky, for political activities.
Khodorkovsky, one of Russia's wealthiest men, was arrested last October and is on trial on fraud and tax evasion charges.
Oil prices have been rising in the past two months partly due to concerns over supply disruptions from Russia linked to Yukos 's problems.
But analysts have said the Kremlin will refrain from upsetting Yukos 's export operations to avoid blame for adding to already substantial increases in oil prices.
President Vladimir Putin has said in recent weeks that Russian oil companies would continue to increase production and exports, and visiting French Finance Minister Nicolas Sarkozy said last week Russian officials had made a similar pledge.
Yukos, which faces a potentially ruining $7 billion tax bill, had planned to boost exports to China to 300,000 bpd by 2006.