Russia's richest man, Mikhail Khodorkovsky, was hauled off his private plane by armed security police in a Siberian airport yesterday and taken back to Moscow for questioning in connection with a widening investigation into alleged theft and tax evasion.
He was subsequently charged with six counts of fraud and tax evasion.
Mr Khodorkovsky's company Yukos, Russia's largest oil producer, has been under criminal investigation for the past four months.
"The head of Yukos is implicated in a series of crimes, including theft by fraud on a large scale, the failure to pay taxes as an organisation and as an individual," said a statement issued by the prosecutor's office in Moscow.
Early yesterday, heavily armed agents of the FSB security service, the former KGB, surrounded and boarded his plane at Novosibirsk airport. A Yukos spokesman said Mr Khodorkovsky went to Siberia "on a business trip" and had every intention of reporting to Moscow prosecutors tomorrow.
"They rushed aboard the plane shouting: 'FSB, drop your weapons'," Alexander Shadrin, a press spokesman for Yukos, told the Ekho Moskvi radio station. "They used special forces in the same way they would deal with a terrorist attack." Citing an anonymous source at the Siberian airport, the Russian online newspaper Gazeta.ru said Mr Khodorkovsky was handcuffed, hooded and kicked several times by FSB agents as they dragged him from the plane.
On Thursday police raided a public relations company in Moscow which has been handling the parliamentary election campaign of the liberal Yabloko party. Mr Khodorkovsky has openly backed Yabloko, which is the main liberal opposition to the Kremlin.
Some experts share Mr Khodorkovsky's opinion that he is being punished by the Kremlin for his support of opposition parties during Russia's current parliamentary elections and that the Kremlin faction of siloviki (former secret police officers in President Vladimir Putin's entourage) are trying to curtail his political ambitions.
Also, he has funded human rights groups and recently bought the weekly newspaper Moskovsky Novosti and appointed a veteran critic of the Kremlin as editor.
Sergei Markov, director of the Centre for Political Studies, said: "Putin will have to take a clear stance on this conflict that is raging within the Russian bureaucracy. I expect major political events to follow very soon."
The legal assault on Yukos began last July with the arrest of Platon Lebedev, a major Yukos shareholder and Khodorkovsky ally, who was charged with defrauding the state in a 1994 privatisation deal. Several other company executives have since been arrested, and a number of company premises searched, in an expanding official campaign that has caused Yukos's shares to plummet on Russia's stock exchange.
Mr Putin has said little about the affair. Some believe Kremlin security hardliners are trying to prevent Mr Khodorkovsky from selling a share of his oil major to a foreign firm. Both Exxon and Chevron have expressed interest in buying a 25 to 40 per cent stake in Yukos, a deal that could be worth up to $20bn (£11.8bn). But earlier this year, another Russian petroleum firm, the Tyumen Oil Company, sold half its stock to BP with no objections from the Kremlin.
Mr Khodorkovsky is the wealthiest of about 20 "oligarchs" who now control about 70 per cent of Russia's economy. The Yukos chief is said to have acquired his empire at cut-rate prices through insider trading and fixed auctions during the free-for-all of the 1990s.
After Mr Putin came to power, the Kremlin attacked the two most prominent opposition-minded tycoons, Boris Berezovsky and Vladimir Gusinsky, seizing much of their property and driving them into exile. The remaining oligarchs quickly pledged to stay out of politics.
But Mr Khodorkovsky, who is widely believed to harbour presidential ambitions, has since seen almost every branch of his far-flung empire come under attack by prosecutors.