LAST January, Mikhail D. Prokhorov, a 42-year-old Russian mining tycoon and a multibillionaire, celebrated the holidays in singular style: with dozens of business associates and an entourage of young Russian women at the exclusive ski resort of Courchevel in the French Alps. The vacation, the French police would later say, featured a private concert by Zveri (the Beasts), a popular Moscow rock group, as well as wads of cash left lying around hotel rooms.

Mr. Prokhorov — tall, svelte, intense and often called Russia’s most eligible bachelor — usually unwound at such blowouts and he once told an interviewer that partying embodied his personal philosophy. His antics in Courchevel, where the police detained him for four days on suspicion of making prostitutes available to his guests, even drew the attention of Nicolas Sarkozy, then the interior minister and now the president of France, who quipped to journalists: “There’s a man who aims to please.” (French police released Mr. Prokhorov without charges but identified him as a witness in their investigation.)

Pleasing friends is one thing. Pleasing Vladimir V. Putin, Russia’s president, is quite another. In one of the more bizarre cases of an apparently forced sale of Russian assets, Mr. Prokhorov’s festivities in Courchevel led — as the byzantine channels of power and wealth in Moscow so often do these days — to his agreement to sell his 26 percent stake in Norilsk Nickel, the world’s largest nickel producer. The buyer was Vladimir O. Potanin, his longtime business partner and a favorite of the Kremlin.

Mr. Prokhorov and Mr. Potanin bought a controlling stake in Norilsk, named for the hardscrabble Siberian city where it is located, for a scant $250 million during the hotly contested privatization of state-owned companies in the mid-1990s. Today, Norilsk produces one-fifth of the world’s nickel, a key alloy in stainless steel, and has a market capitalization of $31.9 billion; its profits doubled last year, to $6 billion, buoyed by high demand for steel in China. Awash in cash, Norilsk in late June closed a deal to buy the Canadian mining company LionOre for $6.4 billion and already owns a controlling interest in the Clearwater Mining Company in Montana.

In an interview on state television, Mr. Potanin said he ended his partnership with Mr. Prokhorov, who Forbes magazine estimates has a net worth of $13.5 billion, because of the embarrassing arrest. They have yet to complete the deal, but the partners said they would unwind their businesses before year-end, leaving Mr. Potanin in control of Norilsk. And who, ask some analysts in Moscow, controls Mr. Potanin?

“In Russia today, no serious deal can be made without approval from the Kremlin,” said Irina Y. Yasina, a researcher at the Institute for the Economy in Transition, a research group led by a former prime minister, Yegor T. Gaidar. “A person like Potanin, without the agreement of the Kremlin, can do nothing.”

UNDER Mr. Putin, the Russian government is establishing vast, state-owned holding companies in automobile and aircraft manufacturing, shipbuilding, nuclear power, diamonds, titanium and other industries. His economic model is sometimes compared with the state-owned, “national champion” industries in France under Charles de Gaulle in the 1950s. The policy of forcing owners of strategic assets to sell their holdings has also been compared to recent nationalizations in Venezuela and other Latin American nations.

Rather than expropriating assets outright, Mr. Putin’s government has exploited minor legal infractions at the target companies to force sales. Either government-controlled companies, or companies run by men seen as loyal to Mr. Putin’s Kremlin, are the beneficiaries.

In 2003, for example, prosecutors went after Mikhail B. Khodorkovsky, chairman of Yukos Oil, then Russia’s largest private company, on accusations of tax evasion. Mr. Khodorkovsky was sent to a Siberian prison, and Yukos went bankrupt. The state company Rosneft later acquired most of Yukos’s assets. Last fall, it was environmental infractions in pipeline construction that forced Royal Dutch Shell and Japanese partners to sell a controlling stake in their $22 billion Sakhalin II oil and gas development to Gazprom, the state gas monopoly.

Then, this June, BP’s local joint venture, TNK-BP, sold its share of a huge gas development after regulators threatened to revoke the license because the field was developed too slowly, which was a technical violation of the terms of TNK-BP’s license. Gazprom, again, was the beneficiary.

Coincidentally, Mr. Prokhorov and Mr. Potanin own a minority stake in that same BP gas field. Their 26 percent stake was not touched, perhaps because of Mr. Potanin’s close ties to Mr. Putin. But in the case of Norilsk, Mr. Prokhorov’s arrest, analysts say, seems to have been a fortuitous accident that gave the Kremlin cover for exerting more control over this strategic metals company.

Mr. Prokhorov and Mr. Potanin both declined to be interviewed. But the end of their partnership is yet another milestone in how the Kremlin and a class of ambitious, enormously wealthy Russian businessmen known as oligarchs do business together.

“Property rights are very conditional in Russia, to this day,” said Olga V. Kryshtanovskaya, a sociologist at the Institute of Sociology of the Russian Academy of Sciences who studies Russia’s business and political elite. The government lets big industrialists “exist only under conditions it considers acceptable,” she said, adding: “When the Kremlin considers a capitalist such as Prokhorov no longer acceptable, he is deprived of his property, by one means or another. Private business exists only by the grace of the state.”

In Norilsk itself, a dirty, desolate city 1,900 miles northeast of Moscow, Mr. Prokhorov’s extravagant lifestyle raised hackles. The city began as a slave labor camp for political prisoners and common criminals in the 1930s, expanding quickly in the 1940s with an influx of prisoners of war. The town’s name, like perhaps no other place in Siberia, is evocative of hardship and the gulag.