Russian billionaire Alexander Lebedev said he doesn't think a search by masked police that paralyzed his bank for hours last week was politically motivated and has filed a slew of court and other complaints in protest.

The sudden arrival Nov. 2 of dozens of masked, heavily armed police serving a search order at National Reserve Bank in Moscow raised fears that Mr. Lebedev, known for his outspoken political views and support of a prominent opposition newspaper, might have become a target for authorities. But the investigators left after several hours with documents and other materials. No charges have been filed against Mr. Lebedev or his bank.

"I don't believe this is some kind of political order from above," Mr. Lebedev said in a telephone interview . He said he suspects the showy search was linked to a conflict around a failing bank that National Reserve had taken over last year at the request of regulators.

National Reserve filed suit in Moscow Friday challenging the court order authorizing the search. Mr. Lebedev also sent dozens of letters to senior Russian officials, including President Dmitry Medvedev and Prime Minister Vladimir Putin, seeking an investigation. There was no immediate response to those, however. Police and other officials refused to comment on the raid.

Known as "masky shows," searches by heavily armed police and prosecutors are a fixture of Russian business life. While the show of force is sometimes justified to get evidence from recalcitrant suspects, the raids are sometimes used as tools of intimidation in business conflicts, business leaders say.

Mr. Lebedev, a former KGB spy, is rare among Russian tycoons in his support of opposition media. He also owns London's Evening Standard and Independent newspapers.

Mr. Lebedev said the highly publicized raid had led to an outflow of deposits from his bank, though its financial stability wasn't threatened.

He said he'd had no informal indications from officials or other contacts about what motivated the raid.

"The point of these things is that no one ever decodes them," he said. "You're supposed to decode them yourself."

The investigators were executing an order from Moscow's Tverskoi Court in a criminal investigation into allegations of fraud at Bank Rossiisky Kapital, which Mr. Lebedev's National Reserve had taken over in 2009.

In his letters to officials this week, Mr. Lebedev said his staff had exposed widespread fraud at Rossiisky Kapital but that authorities refused to open criminal probes. He said the previous owners claimed to have high-level patrons in Russia's security services. But after the government's bank-rescue agency took over earlier this year, several cases were opened, officials said.

"We used some of the documents he gave us" in preparing the complaints, said a senior agency official. He said Rosssiisky Kapital's previous owners stole millions from the bank as it collapsed. "It was a criminal bankruptcy," he said. "NRB [National Reserve Bank] had nothing to do with this." The previous owners couldn't be reached for comment.

The bank-rescue-agency official said the search at National Reserve appeared to be seeking documents about Rossiisky Kapital.

"I don't know why they needed to wear masks," he said. "But sometimes they use crowbars … and this time they waited in the lobby, so I don't see anything terrible."