Investigators and a band of armed, masked police raided the Moscow offices of Russian banker and newspaper owner Alexander Lebedev Tuesday. Mr. Lebedev, who wrote about the incident on his blog, was in the office during the late-morning incident but wasn't detained, questioned or harmed, said his spokesman, Artyom Artyomov. There is no reason to think the incident was part of a plot to intimidate Mr. Lebedev, the spokesman said.

Top managers of Mr. Lebedev's National Reserve Bank helped the investigators who accompanied the masked men to access files and computer records, Mr. Artyomov said, adding that it was unclear what they were seeking.

"We don't understand why they needed these men in black with weapons," he said.

Such raids happened often in the 1990s, when authorities and competing business owners used "mask shows" to frighten and take advantage of rivals, Mr. Artyomov said.

Raids on businesses and banks by authorities and private security forces remain relatively commonplace in Russia, even when minor white-collar or tax crimes are suspected.

Mr. Lebedev this year bought the U.K. newspapers the Independent and the Independent on Sunday; he also owns the London daily the Evening Standard, a stake in the Kremlin-critical Russian newspaper Novaya Gazeta and part of airline OAO Aeroflot.

On his blog, Mr. Lebedev said the investigation appears to be related to his bank's takeover of the Rossiysky Kapital bank during the recent global financial crisis. National Reserve Bank had approached the authorities about possible wrongdoing related to Rossiysky Kapital, but its concerns hadn't been heeded, he said.

An Interior Ministry spokesman told the Interfax newswire that police were dispatched to the office building, which also houses the state technology corporation headed by Russia privatization engineer Anatoly Chubais, to continue an unspecified criminal investigation, without elaborating.

Video surveillance footage posted on Mr. Lebedev's website showed black-clad, masked men carrying automatic weapons mustering at the entrance to the building before working their way in and cooperating with other men in business suits.

On his blog, Mr. Lebedev mocked Russian President Dmitry Medvedev's words that the state shouldn't "create nightmares for business," and facetiously warned readers about engaging in business or supporting opposition newspapers.

Also on Tuesday, Mikhail Khodorkovsky, the former billionaire who once controlled bankrupted oil company Yukos, gave an impassioned final address to a Moscow court in his second trial and told the judge the fate of Russia is connected with the verdict due next month.