SRINAGAR, India (Reuters) - Sanaullah Haq, a convicted Pakistani militant jailed in India died on Thursday in hospital after being beaten by another inmate in an apparent revenge attack for the death of Indian spy prisoner Sarabjit Singh, threatening already fraught relations between the two nations.
The death of Haq, also known as Sanaullah Ranjay, came a week after Singh died in Pakistan, leading to furious protests in India and criticism of Prime Minister Manmohan Singh's government for going soft on its western neighbour.
"Although it's scant consolation I'd like to offer a sincere apology to the family of Sanaullah Haq & my sympathies for their loss," Omar Abdullah, the chief minister of Jammu and Kashmir where Haq was imprisoned, wrote on Twitter on Thursday.
Pakistan, which is due to hold an election on Saturday, demanded an investigation into Haq's death and said the attack was "a matter of deep concern." Home Minister Sushil Kumar Shinde said Haq's body will be returned to Pakistan.
Haq, 64, had been in and out of Indian jails since 1989 for spying and "subversive activities," a senior police officer said. He was badly beaten last week in the prison gardens by a jailed Indian soldier, the prison superintendent said at the time, in an apparent revenge attack for the similar, fatal beating of Sarabjit Singh, the convicted Indian spy who died in Pakistan. Singh's family says he was innocent.
Singh was given a formal funeral, including a 21 gun salute, by the government of Punjab in his home town close to the border with Pakistan.
India and Pakistan have fought three wars since the partition of British-ruled India in 1947. They began a peace process in 2004 and have gradually improved trade ties, but remain deeply suspicious of each other. Relations have been strained by several incidents this year.
The Pakistani government issued a travel advisory to its citizens on Tuesday, asking them to "exercise due caution and care" in India. It said the safety and security of Pakistani visitors in India, particularly those at an annual pilgrimage, could be in jeopardy.
In January, two Pakistani and two Indian soldiers were killed in an outbreak of violence in the disputed territory of Kashmir. It was the worst clash there since India and Pakistan agreed to a ceasefire nearly a decade ago, leading to angry reactions from both sides.
The Indian army launched a "massive" operation this week along the de facto border with Pakistan known as the Line of Control, after a group of militants were spotted in north Kashmir, said Brijesh Panday, an Indian army colonel.
The police chief in the snow-bound forested district told Reuters the army was still hunting for the suspected militants.
Despite the recent strains, India-Pakistan relations have improved after nose-diving in 2008 when gunmen killed 166 people in Mumbai in a three-day rampage that India blamed on a Pakistani militant group. Last year, India hanged Ajmal Kasab, a Pakistani citizen convicted of taking part in that attack.
Nawaz Sharif, seen as the front-runner in Pakistan's election race, said on Wednesday he would not allow militant groups to attack India from his country and would work to improve ties with rival New Delhi if elected.
Reporting by Fayaz Bukhari; Additional reporting and writing by Anurag Kotoky in NEW DELHI; Editing by Frank Jack Daniel and Michael Perry