Russian tycoon Alexander Lebedev, the owner of Britain's Independent and London Evening Standard newspapers, asked Prime Minister Vladimir Putin on Friday to intervene in a criminal investigation linked to his bank.

The billionaire ex-KGB agent, part-owner of an opposition paper, described the probe connected with his National Reserve Bank (NRB) and a police raid on its offices last year as an attack by criminal gangs working with the authorities.

"I believe we are dealing with an organised mafia group making raids on my business in the guise of 'carrying out orders from above'," he said in an open letter to Putin on his blog.

Lebedev said the group included highly placed current and former officers of the Interior Ministry and the Federal Security Service (FSB), the Soviet KGB's main successor, and "corrupt officials supervising securities."

The November raid by armed police was linked to the suspected embezzlement of 450 million roubles ($15.5 million) from the bank Russian Kapital, which Lebedev's NRB bought in 2008. Lebedev was due to testify in court on Friday.

"Respected Vladimir Vladimirovich! I am requesting you intervene in the situation, the bandit raid by werewolves in epaulettes," Lebedev said, using a term referring to corrupt law enforcement officers.

A spokesman for Lebedev expressed concern that the probe could be extended to NRB itself. "We believe that prosecutors may be trying to link Lebedev with the current embezzlement investigation," spokesman Artyom Artyomov said by telephone.

Kremlin critics say the government uses raids on businesses as a way to put pressure on political opponents. Lebedev is part-owner of the opposition newspaper Novaya Gazeta, which in December announced a partnership with WikiLeaks to expose corruption in Russia. He has also run against Putin's ruling United Russia Party in local elections.

Lebedev, who also owns a 15.5 percent stake in the Russian flag carrier Aeroflot, is Russia's 40th richest man with reported wealth of $3.1 billion according to the respected Finans magazine.

Lebedev has styled himself a critic of the Kremlin, but has seemed to tread carefully and not cross his former KGB colleagues, who make up the largest bloc of Kremlin support for Putin, a longtime KBG officer and former FSB chief.

The National Reserve Bank bought Russian Kapital at the behest of Finance Minister Alexei Kudrin and central bank chief Sergei Ignatyev, Lebedev said, after it was no longer able to pay its debts at the height of the financial crisis.

The purchase of the bank for 5,000 roubles was carried out with credit furnished by the central bank and NRB started to repay Russian Kapital's debts, he said. Artyomov said Lebedev sold the bank to the Deposit Insurance Agency for the same amount he bought it for and returned the borrowed funds to the central bank.