A lawyer for jailed Russian tycoon Mikhail Khodorkovsky says the inmate was attacked in prison and had to receive medical attention.
Yury Schmidt Saturday said another prisoner slashed Khodorkovsky in the face with a handmade knife in the early morning hours Friday.
Khodorkovsky, the former head of oil giant Yukos, received medical attention and his wound was stitched.
Interfax news agency reports a Federal Prison Service spokesman is downplaying the incident, saying a preliminary investigation indicates the attack stemmed from an argument between Khodorkovsky and a young inmate.
Khodorkovsky is serving an eight-year jail term at a Siberian prison camp following a conviction on tax evasion and fraud charges.
Khodorkovsky's supporters say the Kremlin is punishing him for supporting the political opposition, a charge Russian officials deny.
Some information for this report was provided by AP.