A Kremlin official with a reputation for dissenting from the official line attacked the conviction on Tuesday of Mikhail Khodorkovsky, former head of the Yukos oil company, and the dismantling of the company.

"I must say that the verdict is a result of the diseases that have metastasized the economy and our society," Andrei N. Illarionov, an economic adviser to President Vladimir Putin, said at a news conference. "During these two years the case caused tremendous damage to our country."

Khodorkovsky, along with business partner Platon Lebedev, was convicted of tax evasion and fraud related to the privatization of several companies in the 1990s. The Russian government said the trial was part of a crackdown on financial crime and that it shows that no one is beyond the law. The two men's supporters and many human rights group regard the charges as Kremlin retaliation for Khodorkovsky's financing of opposition groups.

In parallel with the criminal prosecution, Russian authorities served Yukos with tax bills totaling $28 billion. In December, the company was gutted by the forced auction of its prime asset, Yuganskneftegaz, to pay taxes.

Illarionov, 43, has a reputation as the only maverick in a Kremlin where dissent is kept private. In January, Illarionov was removed as Russia's envoy to the Group of Eight, the world's leading industrialized nations and Russia, after he criticized the sale of Yuganskneftegaz.

The unit, which pumped a million barrels of oil a day, was taken over by a state-controlled enterprise, Rosneft, after first being purchased at auction by a unknown front company.

In January Illarionov called the sale the "swindle of the century" and criticized the Kremlin's centralization of power, its control of the media and the general direction of the state's economic policy. He said Russia risked becoming a Third World country.

On Thursday, he attacked again, lambasting the court that sentenced Khodorkovsky and Lebedev to nine years in prison.

"From my point of view, this court demonstrated a profound lack of competence in terms of economy and jurisprudence, and statements made by the sides showed their lack of good command of the Russian language," he said. "As a person who watched the hearings for some time, I was shocked by the low level of competence of the people who represented the state. And I personally felt and still feel very ashamed of the state that has to represent itself in such a way."

Illarionov also said: "What is happening now will bring about very deep and very serious changes in the economic, political and public system in the country. The magnitude of these changes is hard to perceive at this point, but the damage caused to the country is already so big that it is hard to estimate it in full."

There was no response from the government.

Lebedev appealed his sentence Thursday, and Khodorkovsky is also expected to appeal.

Andrei N. Illarionov is the Kremlin's most outspoken dissenter.