MOSCOW, January 25 (RIA Novosti) -- The jailed founder of oil major Yukos, Mikhail Khodorkovsky, has been placed in solitary confinement for breaking prison rules, a penitentiary service official said Wednesday.

"The head of the [prison] colony in Krasnokamensk [the Siberian town where Khodorkovsky is being held] made the decision, and he had the right to do so," Yury Kalinin said. "Khodorkovsky has already been reprimanded. He was put in solitary confinement when it was discovered that he had documents and items that prisoners are not allowed to keep."

Kalinin said the prison's administrative committee had decided to place the former oil tycoon in solitary confinement for five days.

Commenting on the punishment, Khodorkovsky's lawyer Yury Shmidt said the authorities purposely took this action to prevent the possibility of a milder sentence and even parole.

"Parole would be out of the question if punishment were imposed [on Khodorkovsky]," the lawyer said.

Khodorkovsky has been serving an eight-year sentence in Krasnokamensk in the Chita Region for tax evasion and fraud since October 15, 2005.