This was a second such gang-related attack in the prison following the attack on the underworld don Abu Salem two months ago.

Mehdi was immediately rushed to the government-run JJ Hospital in central Mumbai where he was admitted and is undergoing treatment.

According to prison sources, Mehdi is a prominent member of the Abu Salem gang. He is presently incarcerated on charges of threatening a real estate promoter and trying to extort money from the promoter.

On Saturday morning, he had an altercation with some associates of the Putra gang in the prison that led to the attack on Mehdi by five members of the Putra gang. The names of the attackers were not immediately known. Mehdi received injuries to his hands and face, the sources said.

Earlier on July 24, Abu Salem was attacked with a sharp spoon in the Arthur Road prison by Mustafa Dossa, a close confidante of underworld don Dawood Ibrahim Kaskar. Abu Salem received serious injuries to his nose and neck.

Abu Salem was then moved out and sent to the Taloja prison in Navi Mumbai, while Dossa too was moved out to the Thane prison. Security was beefed up at the Arthur Road prison after this incident, but once again the slack security arrangements at the prison was exposed by the second incident.

In another development, Maharashtra Home Minister R.R. Patil on Friday, warned cell service operators of stern action if they do not verify documents before issuing SIM cards. Patil's warning came in the background of recent threats by alleged terrorists sending e-mails through cell phones claiming responsibility for the Jama Masjid firing in New Delhi.

Patil told the cell service operators that the government has taken serious view of reports that the alleged terrorists had sent the e-mails using SIM cards with fabricated documents. He warned that all SIM cards issued without proper verification would be seized.

The Mumbai police and the Anti-Terrorist Squad (ATS) are on the lookout for a person who had procured a cell SIM card in the name of a female for sending the e-mail related to the firing at the Jama Masjid.