The Russian stock market showed a tentative recovery on Tuesday, a day after a steep plunge prompted by the arrest and jailing of the head of the oil giant Yukos and Prime Minister Mikhail Kasyanov called for steps to stabilize Russia's financial markets.

　　But one of the country's most prominent politicians warned that the arrest of Mikhail Khodorkovsky could destroy investors' trust in Russia and an influential lawmaker called on the Prosecutor General's office to open an investigation of an oil company that is soon to merge with Yukos.

　　Khodorkovsky was jailed Saturday on charges of tax evasion, fraud and forgery. Many perceive the four-month investigationsintosYukos oil and his other companies as an attack organized by some of President Vladimir Putin's associates to avenge the tycoon's political activities, including funding opposition parties in the run-up to the December 7 parliamentary elections.

　　Yukos shares and the Russian stock market closed higher on Tuesday, but the boosts did not offset the losses of Monday's trading. Yukos gained 3.3 per cent after falling 15 per cent a day earlier, and the benchmark RTS index rose 4.93 per cent against Monday's 10-per cent plunge.

　　"Yesterday the situation was tense, but there is no need to panic. We have to take all measures to stabilize and restore the market," Kasyanov said earlier Tuesday. "Everyone, in his own position, should make efforts to restore the markets," he said without elaborating.

　　Boris Nemtsov, a leader of the liberal Union of Right Forces party, suggested in a newspaper interview that severe damage had already been done.

　　"The arrest of Khodorkovsky is a signal that you shouldn't have dealings with us, that we don't live under law and with the understanding that in this country it is impossible to plan anything for the long term," he was quoted as saying in the newspaper Nezavisimaya Gazeta.

　　Nemtsov's party is one of two opposition groups that Khodorkovsky had helped fund.

　　Also Tuesday, a Moscow court granted a request to keep a close Khodorkovsky associate, Platon Lebedev, in jail for another two months to allow them time to build their case, Interfax reported. Lebedev had been scheduled to be released Thursday. He now can be held until December 30.

　　Interfax said the request for extending his detention was based on concerns that if released he could flee the country or try to pressure witnesses.

　　Lebedev, a top Yukos shareholder and board chairman of Menatep Group, a holding company that is a major shareholder in Yukos, was detained in July on charges of stealing state assets during the 1994 privatization of a fertilizer plant.

　　His arrest grew out of an investigation requested by pro-Kremlin lawmaker Vladimir Yudin. On Tuesday, Yudin requested an investigation of the privatization of the Sibneft oil company, Interfax reported.

　　Yukos recently completed arrangements for merging with Sibneft, a move that would create the world's fourth-largest oil-producing company.

　　'No complaints'

　　Khodorkovsky, whose fortune was estimated at US billion by Forbes magazine, is being held at Moscow's Matrosskaya Tishina detention complex, parts of which are overcrowded. But his lawyer Anton Drel said Tuesday that the tycoon "has no complaints" on his conditions.

　　Drel said he had asked the court to release Khodorkovsky on bail or on guarantee that he would not flee the country or allow him to be put under house arrest.

　　Putin on Monday staunchly defended the prosecutors' decision to arrest Khodorkovsky, and said there was no basis for fears that the government aimed to redistribute the state property that was privatized following the 1991 Soviet collapse.

　　The probesintosYukos also has resulted in charges against Vasily Shakhnovsky, who until Monday was the company's chief operating officer. He resigned Monday after a regional legislature in Siberia appointed him to represent the region in the Federation Council, upper house of the Russian parliament.

　　Council members customarily have legal immunity. But prosecutors in Siberia are investigating whether Shakhnovsky's appointment to the Federation Council was legal, Interfax reported.