Imprisoned Russian oil tycoon and Kremlin critic Mikhail Khodorkovsky has decided not to run in elections to an umbrella opposition body next month, he announced, saying he could not be useful in his "present circumstances."

"I am grateful to those who thought me deserving of being part of this new structure. But I have rejected the idea of putting forward my candidacy," Khodorkovsky said in comments carried by supporters' khodorkovsky.ru website.

The elections to the 45-seat Coordination Council of the Russian Opposition, which activists hope will unite the country's fractured opposition groups, are scheduled for October 20-21.

Khodorkovsky said his decision was "due primarily to the fact that in my present circumstances I cannot be of use for the resolving of practical issues."

The former Yukos oil giant boss has been convicted in two separate trials since his 2003 arrest, and is not eligible for release until 2016. His two bids for parole have been unsuccessful.

Khodorkovsky insists he is a victim of a politically motivated campaign, a claim denied by the Kremlin.