Moscow ? Russia’s prime minister waded into the political turmoil after prosecutors’ actions against the Yukos oil company, saying Friday he was “very troubled” by the freezing of its stocks.

“The arrest of shares of a private company that is traded on the market is a new phenomenon, the consequences of which are hard to define, since it’s a new form of influence,” Prime Minister Mikhail Kasyanov said in the southern city of Nalchik, in remarks shown on Russian television.

The statement appeared to be a sign of defiance toward President Vladimir Putin, who flatly warned his Cabinet on Monday against interfering in prosecutors’ work against Yukos.

“There will be no meetings and no bargaining in regard to the activities of the law enforcement structures,” Putin had said Monday, adding an appeal to the Cabinet not to meddle in the Yukos case.

Russian analysts predicted a long period of uncertainty after the sequestration of the stocks and the exit of the Kremlin operative most closely identified with the pro-business policies of former President Boris Yeltsin.

Thursday night, the Kremlin announced its chief of staff, Alexander Voloshin, was departing, capping days of rumors that he had resigned over Saturday’s arrest and jailing of Yukos head Mikhail Khodorkovsky, Russia’s richest tycoon.

Hours earlier, prosecutors froze a huge chunk of Yukos shares, plunging the stock market into its second nosedive this week.