The former head of Russian oil giant Yukos says the government takeover of the company's main asset has inflicted severe damage on the Russian economy.

In a letter published Tuesday, Mikhail Khodorkovsky said Moscow's approval for state-owned Rosneft to purchase Yukos' largest subsidiary, Yuganskneftegaz, was the most destructive economic event since Russian President Vladimir Putin took office.

The former oil tycoon, imprisoned on alleged tax fraud, said Russian authorities want to lock him away because they are afraid he will seek revenge. He denied any such intention, and said he would like to play a role in helping Russia prosper.

Meanwhile in Moscow today, Mr. Putin's economic advisor Andrei Illarionov said this month's government-forced sale of Yukos' main asset was "the fraud of the year."

Some information for this report provided by AP, AFP and Reuters.