He was rushed to Mumbai's JJ Hospital due to chest pain.
One accused was acquitted by the court.
"Salem was attacked by Mustafa Dossa with a sharp object. He was injured and doctors are treating him inside the jail. A police team is at the spot," Vasant Tajane, Senior Inspector at N M Joshi Marg police station, told PTI.
Salem, who was extradited from Portugal in 2005, is accused of delivering an AK-56 rifle at the residence of Sanjay Dutt and various other weapons to co-accused. Siddiqui and Ansari, too, are accused of delivering weapons at different places. CBI had recorded Salem's statement, in which he had confessed to the crime. Also, Sanjay Dutt and other convicts had named him and his associates for the role that they had played in the blasts.
Another accused Riyaz Siddiqui was sentenced for 10 years
"India is my country and I will stay here and do business to earn a livelihood," Qayyum said.
The detailed role of the six convicts in the case, whose trial was separated from the main one, which concluded in 2007.
Merchant had arranged the finance for the blasts, and was also linked to conspirators Tiger Memon and Dawood Ibrahim.
Relatives and victims felt that justice had been delayed.
The Maharashtra government's decision to hand over all the cases against underworld don Chhota Rajan to the Central Bureau of Investigation has not gone down well with the Mumbai Police with several senior officials criticising the move stating that it has raised doubts over their ability.
A chronology of events in the case in which the main trial ended in 2007.
Prison superintendent, who has been charged with torturing the underworld don, reveals the perks and privileges the gangster enjoyed behind bars.
Gangster Abu Salem has denied in his statement before the Terrorist and Disruptive Activities (Prevention) Act court in Mumbai that he went to the house of Bollywood actor Sanjay Dutt.
A day after gangster Abu Salem was shot at in Taloja jail, four security personnel were suspended on Friday pending a high-level probe even as his lawyer is planning to move Portuguese authorities for his repatriation. An attempt to murder case was also registered against his assailant Devendra Jagtap alias JD.