MOSCOW — Russian media magnate Vladimir Gusinsky was released from a Moscow jail Friday night, four days after an arrest that raised alarms about the prospects for press freedom in Russia and presented President Vladimir Putin with the first political challenge of his young presidency.

Gusinsky, the 47-year-old head of a media empire that has at times been harshly critical of the Kremlin, walked out of Moscow's shabby Butyrka prison at about 10 p.m. Friday night after signing a letter promising not to leave Moscow.

Gusinsky arrived later at his company headquarters in the center of Moscow, for a meeting with his top managers.

Earlier, Gusinsky was formally charged with "large scale embezzlement" in connection with the 1996 privatization of a St. Petersburg television station, in which Media-MOST subsequently bought 70 percent of the shares.

The investigation, now in its second year, has been widely seen in Russia as a pretext for a final act in a long-running power struggle between the Kremlin and Gusinsky.

Russian authorities have denied any political overtones to the arrest but at a press conference Thursday in Germany, Putin said he thought that Russia's prosecutor general had gone "too far" in arresting and jailing Gusinsky.

However, at another press conference Friday in Berlin, Putin said he had no reason to believe that the prosecutor's office had acted "unlawfully." He also noted that Gusinsky would be eligible for release under a recent amnesty that applies to people who have been awarded special government honors. The Gusinsky case is expected to take on political dimensions on Wednesday when the Russian Parliament reconvenes. Some political leaders have already said that the controversy may affect support for the president's legislative effort to tighten the Kremlin's control over regional governors.

Already, the arrest has aroused protests from politicians, journalists and business leaders, both Russian and foreign. American Jewish leaders and 52 members of Congress had appealed to Putin to release Gusinsky, who is also the head of the Russian Jewish Congress.