The British-Pakistani national, sentenced to death for killing Wall Street Journal reporter Daniel Pearl, attempted to take his life in Hyderabad central jail in Sindh province on Wednesday night, senior prison official Akram Naeem said.
Sheikh, 41, was stopped in time by jail officials when he tried to hang himself inside his cell, Naeem said.
"He is kept in a separate cell and section of the jail as he is no ordinary criminal," he said.
He was convicted and sentenced to death by an anti- terrorism court in Karachi after he was found guilty of planning and killing Pearl.
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He had admitted to the kidnapping of Western tourists in India and served time in jail from 1994 to 1999 before being released in exchange for passengers of hijacked Indian flight.
"We have filed a case against him for attempted suicide and he can face additional punishment now," he added.
Sheikh's lawyer has said that they are waiting for the court to hear their appeal against the death sentence on the ground that the self proclaimed 9/11 mastermind, Khalid Sheikh Muhammad, had admitted to killing Pearl.
Another jail official said that Sheikh was kept in solitary confinement after the Mumbai 2008 terror attacks.
"After the incident of the hoax calls he made to then President Asif Ali Zardari pretending to be the Indian foreign minister he was kept in solitary confinement and is allowed into the courtyard outside his cell under guard for a short time everyday," he said.
"He is a very intelligent, strong and sharp criminal with dangerous designs. So his attempt to commit suicide comes as a surprise," the official said.
The Dawn newspaper had confirmed the story that Sheikh had made the hoax calls after the Mumbai terror attacks using a phone smuggled into his cell and with British SIM card.