LAHORE: Sarabjit Singh, an Indian citizen jailed in a Pakistani prison on espionage and terrorism charges, was attacked and seriously injured by fellow inmates in a Pakistani jail on Friday in an incident that could inflame the uneasy relations between the two nations.

Singh, who was serving his sentence in Lahore’s Kot Lakhpat, was attacked with “bricks and blades” when he came out for lunch from his special barrack. The prison administration confirmed Singh suffered serious wounds to his head.

“Sarabjit was having tea with fellow prisoners Muhammad Muddasar and Amir, also condemned for death sentence in murder cases. They exchanged hot words with Sarabjit and attacked him with bricks and blades,” jail official Munawar Ali said.

Singh was immediately rushed to Jinnah hospital for emergency medical aid where doctors said he was undergoing treatment.

It was not immediately clear what had prompted the other prisoners to attack the Indian inmate.

Singh was convicted in 1991 for spying and carrying out four bombings which killed 14 people in Lahore and Faisalabad in 1990. He has been languishing in jail since his conviction. His family says he is innocent.

The prison administration has suspended the Assistant Superintendent, the head warden and the warden for negligence leading to the attack on Singh.

Four years ago, Pakistan's then-president Gen (retd) Pervez Musharraf stayed the execution after appeals for clemency from India's Prime Minister Manmohan Singh.

Nuclear-armed India and Pakistan have fought three wars since the partition of British-ruled India in 1947, but they began a peace process in 2004.

Despite better relations, the neighbours remain deeply suspicious of each other.

India blamed Pakistani militants for carrying the 2008 attacks in Mumbai that killed 166 people over three days and raised questions over the involvement of Pakistani security services.