MOSCOW, April 15 (RIA Novosti) - The Russian federal penitentiary service said Saturday it had launched an inquiry into an alleged assault on jailed tycoon Mikhail Khodorkovsky.

"An inquiry is under way. Khodorkovsky has no penetrating wounds, he just has a scratch on his nose. His health is not in danger," service head Yury Kalinin told RIA Novosti adding that the details of the incident would be known Monday.

However, Khodorkovsky's lawyer Yury Schmidt said his client, the founder and former CEO of oil company Yukos currently serving an eight-year term sentence for tax evasion and fraud in a penal colony in East Siberia, had been assaulted by another prisoner Thursday night when he slept.

The lawyer said Khodorkovsky's defense team was planning to obtain all details of the incident.