Armed police on Tuesday swarmed into the Moscow headquarters of a bank owned by Russian media tycoon Alexander Lebedev, who watched helplessly as they rifled through company files, his spokesman and police said.

Up to 50 masked officers raided the National Reserve Bank, jumping turnstiles to enter the offices and search for certain documents, Lebedev's spokesman, Artyom Artyomov, told The Associated Press.

"What do they need this idiotic show for?" Artyomov asked. "Why do they come in here with their guns and masks? If they need a file, they can come with a piece of paper and just ask," he said.

City police spokesman Viktor Biryukov confirmed to the AP that the raid was part of an ongoing criminal investigation. He would not elaborate.

The bank later issued a statement saying that police had produced a court order for the search in connection with transactions made by one of the bank's clients in 2008.

Novaya Gazeta, a Russian opposition newspaper that Lebedev finances, said in a blog post that the police officers were interested in documents concerning Rossiisky Capital, a bank that was taken over by the National Reserve Bank.

Lebedev, who owns two British newspapers, is not known to be in conflict with the Kremlin. His fiercest political and business rival in recent years has been Yury Luzhkov, the Moscow mayor who was ousted in September. Some view Lebedev as a more liberal oligarch than those who follow the Kremlin line more closely.

He issues vague criticisms of corruption and authoritarianism in Russia from time to time, but always stops short of holding Prime Minister Vladimir Putin or President Dmitry Medvedev personally responsible, leading others to consider him a mere instrument of the Kremlin — living proof that Russia is a business-friendly democracy.

Raiding company property and seizing computers and documents is common practice among Russia's law-enforcement agencies. In many cases corrupt police act on behalf of rival businesses to seize ownership documents and potentially incriminating files.

The police left the bank after a few hours, but about 10 investigators wearing suits remained to continue the search, Artyomov said.

Lebedev recently bought Britain's Independent newspaper, owns the London Evening Standard, and is part-owner of Russia's national carrier Aeroflot.