UPDATE 2-Rosneft fights YUKOS injunctions, oil keeps flowing

* Rosneft confirms U.S., British court injunctions

* Company says no material impact, honouring all contracts

* U.S. injunction partly overturned

* Company to challenge London court ruling

(Adds details, analyst comment, background, share price)

By Robin Paxton

MOSCOW, March 18 (Reuters) - Rosneft, the state-run firm behind a fifth of Russia's oil output, has challenged U.S. and British court injunctions brought by managers of defunct rival YUKOS and says oil supplies will not be harmed by the cases.

Rosneft (ROSN.MM) confirmed on Thursday that managers of YUKOS, the former oil giant destroyed by the Kremlin, had won injunctions in New York and London to freeze assets in relation to a $400 million award by a Dutch court to YUKOS last year.

The U.S. case, however, had already been partly overturned and could be thrown out completely within 60 days, Rosneft said in a statement. It will also challenge the London ruling.

"Rosneft is fully meeting all of its commitments to supply oil and oil products, including its export contracts," the company said in the statement. "There are no restrictions in place on payments for oil in U.S. dollars."

Russia dissolved YUKOS, once Russia's largest oil producer, in 2007 after hounding the company for massive back-tax claims. Rosneft, whose rapid ascent was built largely on assets once belonging to YUKOS, has been the key contributor to an increase in national oil production that has pushed Russia ahead of Saudi Arabia as the world's largest crude producer.

Trade sources, who revealed details of the injunctions to Reuters this week, said the court action by YUKOS managers had affected some payments to Rosneft by foreign customers and could jeopardise delivery of the firm's oil abroad. [ID:nLDE62F22Z]

The injunctions are an attempt by YUKOS to recover payment of the approximately $400 million awarded by the Dutch court to a unit of the defunct company, YUKOS Capital.

Analysts said Rosneft would suffer no material impact from either case and that the company had already allocated related funds as a short-term debt obligation in its accounts for 2009.

Its shares, up 0.4 percent by 1410 GMT, traded in line with the wider Moscow market but underperformed its closest peer, LUKOIL (LKOH.MM), which was up 1.5 percent.

Even in the worst case scenario for Rosneft, the injunctions could affect no more than $400 million -- small change for a company that brought in revenues of $46.8 billion last year.

"This legal issue does not put Rosneft's existing exports or payment procedure in danger," said Renaissance Capital analyst Alexander Burgansky.

But the cases, part of the "life-long litigation" promised by YUKOS, could presage other, much bigger cases.

Former YUKOS managers, creditors and shareholders took Russia to Europe's top human rights court this month, accusing Moscow of destroying the firm through illegal tax demands. They are seeking a record $98 billion in damages. [ID:nLDE6231Y1].

"This entire affair is right at the nexus of politics and business," said an industry source, who declined to be named.

"Despite Russia's rhetorical support for the forums in which the decisions are being made, enforcement against the Russian national oil champion is unlikely."

COURT BATTLES

YUKOS directors say the firm was destroyed by a Kremlin-inspired political campaign during the presidency of Vladimir Putin, who was consolidating power at the expense of the business tycoons who struck it rich in the chaotic 1990s.

Russian officials say the company was a corrupt empire that needed to be brought to account. Former YUKOS owner Mikhail Khodorkovsky is serving eight years in a Siberian jail for fraud and tax evasion and could face a further 22 years behind bars if convicted in a second trial under way in Moscow.

The latest legal twist began on Feb. 8, when YUKOS Capital won a temporary injunction in the Federal Court of the State of New York, which prevented payments for its oil.

Thursday's statement was the first by London-listed Rosneft, in which it told investors about the injunctions. It also said this ruling was overturned on Feb. 17 after it argued its case.

In a further hearing on March 17, the court said it had no jurisdiction over the case and could only rule on claims related to Rosneft assets in New York state. The plaintiff has 60 days to find such assets or the case will be dropped, Rosneft said.

In London, YUKOS Capital won an injunction on March 11 to freeze some Rosneft assets in England and Wales. "Rosneft considers this order to be groundless and is taking all the necessary measures to protect its interests in court," it said.

"The amount of property frozen in the English court order is not significant for Rosneft's commercial activities and cannot influence the company's ability to fulfil its commitments."

An official at the High Court's Commercial Court Listing Office said no date had been set for an appeal hearing and that details of the recent hearing were closed to the public.

British courts can, on occasion, order the freeze of assets held overseas. In January 2008, ExxonMobil (XOM.N) secured a worldwide $12 billion freeze on assets belonging to Venezuelan state oil firm PDVSA, but the decision was later reversed. (Additonal reporting by Dmitry Zhdannikov in Moscow and Tom Bergin in London; editing by Anthony Barker)