Vladimir Potanin: Accused of getting Norilsk Nickel on the cheap

Another leading industrialist, Vladimir Potanin, has been ordered to hand over $140m in connection with the privatisation of Russia's largest metal producer, Norilsk Nickel.

The Russian Prosecutor-General's office has accused him of not paying enough for the company's privatisation in the mid-1990s.

And prosecutors again raided the offices of the media magnate Vladimir Gusinsky, a critic of the Kremlin, who was jailed for four days last month.

It is clear that open season has been declared on the oligarchs

Investment analyst Eric Kraus

They seized bundles of documents from the headquarters of Mr Gusinsky's Media-Most - Russia's leading independent media group.

For the first time the offices of the group's flagship NTV television station were also raided.

Prosecutors told Interfax news agency that the seizures were part of an investigation into the 1997 privatisation of the Saint Petersburg television station Russkoye Video.

The Media-Most group also includes Echo Moscow radio station and Sevodnya daily newspaper - popular and outspoken media.

It was the second such move against Media-Most in three months. Mr Gusinsky has been charged with defrauding the government in a privatisation deal.

Media-Most lawyer Pavel Astakhov said: "There is only one goal - to paralyse the activity of Media-Most and the mass media that are part of the holding."

Vladimir Gusinsky: His media have been outspoken on Chechnya

Controlling stakes in many of Russia's largest companies were sold under controversial shares-for-loans schemes, which enabled a few industrialists to build up lucrative empires.

President Vladimir Putin has said he wants to cut Russia's richest businessmen - the so-called "oligarchs" - down to size.

But Mr Gusinsky's detention last month triggered international concern, and was widely seen as punishment for his media's criticism of the Kremlin.

The offices of Gazprom, Russia's giant state gas monopoly, are also reported to have been raided by police.

The BBC's Moscow correspondent Steve Rosenberg says there is no indication that the Kremlin is directly involved in any of these incidents.

But taken together they suggest that certain elements of Russia's business elite, which once flourished under former president Boris Yeltsin, may be about to have their power and influence taken away.

"It is clear that open season has been declared on the oligarchs," commented Eric Kraus, an analyst at NIKoil investment bank.