UPDATE 2-BP says Russian agents search its Moscow office

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By Dmitry Zhdannikov and Tanya Mosolova

MOSCOW, May 20 (Reuters) - Russian security service officers were searching the headquarters of oil major BP (BP.L: Quote, Profile, Research, Stock Buzz) in Moscow on Tuesday for the second time in the two months, adding pressure on the company amid widely rumoured buyout talks.

BP's Russian venture, TNK-BP, is the subject of long-running market speculation that the Kremlin wants a state company along the lines of gas monopoly Gazprom (GAZP.MM: Quote, Profile, Research, Stock Buzz) to buy out the Russian billionaires who own half the company.

"A dozen people came in this morning, the server is down. Some employees were told to switch off their computers, some had to leave the office. They said they were looking for Gazprom-related documents," an industry source told Reuters.

A BP spokesman confirmed searches were taking place at the company, but gave no details.

A spokesman at TNK-BP said his company's offices were quiet, and he knew nothing about the search at BP. The Russian Federal Security Service (FSB) declined to comment.

In March, Russian law enforcement agencies conducted searches at the Moscow offices of BP and at TNK-BP, Russia's third-largest oil producer and which is half-owned by BP.

At that time, a Russian TNK-BP employee was charged with industrial espionage. In both searches, FSB officers were looking for documents related to Gazprom, sources close to the company said.