Eighteen Palestinian prisoners and two Israeli prison guards have been reported lightly wounded during a riot on Thursday at Shikma prison in southern Israel.
Prison officials said the riot erupted when officers tried to search a cell after a prisoner was found with a sketch of the jail. Officers then moved in, firing tear gas.
Officials issued a statement saying the prisoners vigorously resisted the entry of the guards, began banging on their doors, throwing sharp objects and setting paper on fire.
Palestinian officials said the riot was sparked by prisoner complaints about conditions and was not connected with Palestinian demands for Israel to free some 6,000 prisoners as part of recent peace moves.
Israel has agreed to free several hundred Palestinians but says none of those suspected of direct involvement in the killing of Israelis will be released.