Extradited gangster Abu Salem and Mohammad Mustafa Dossa, a close aide of fugitive Dawood Ibrahim, have been shifted to two separate jails following the altercation between the two inside the Arthur Road Jail.
The case has been handed over to the city police's crime branch for investigation.
While Salem has been shifted to the Taloja jail in Navi Mumbai, Dossa has been transferred to the Thane Central Prison, senior jail officials said.
42-year-old Salem, a key accused in the 1993 serial blasts case, was attacked by Dossa and his associate with a sharp spoon on Saturday outside their barrack following a heated argument.
An FIR was lodged against Dossa and his accomplice with the N M Joshi Marg police station.
Salem has been lodged inside the Arthur Road jail since his extradition from Portugal in 2005 and is facing trial in nine cases, including two murders.
Dossa was deported from Dubai in March 2003 and is also facing trial in the 1993 blasts case.
Dossa is accused of having supervised the landing of weapons and explosives in Maharashtra's Raigad district prior to the explosions on March 12, 1993, which killed 257 persons and injured several others.