An Indian national on death row in Pakistan died Thursday from injuries sustained in an attack by fellow inmates last week.

Sarabjit Singh, who was sentenced to death in 1991 on espionage charges, died early on Thursday, a senior doctor at Jinnah hospital in Pakistan’s eastern city of Lahore announced.

He was in a comatose state for the last five days after sustaining several injuries, including a fractured skull, when six prisoners attacked him by hitting his head with bricks on Friday last week, AFP reports.

Singh’s lawyer Owais Sheikh confirmed the death and said that the body “has been moved to the hospital mortuary”. Sheikh earlier said that his client had received threats following the execution of Mohammed Afzal Guru, a Kashmiri separatist, in New Delhi for his role in a deadly Islamist attack on the Indian parliament in 2001.

Singh was convicted for his alleged involvement in a series of bomb attacks in Pakistan’s Punjab province that killed 14 people in 1990, reports AFP. His mercy petitions were rejected by the courts and former president Pervez Musharraf.

The Human Rights Commission of Pakistan condemned the attack on Singh as a “dastardly act” and called on the government to launch a thorough inquiry into the incident and bring the perpetrators to justice.