"The remission was granted on the advice of the prime minister to honour the appeal of the Supreme Court of India to the government of Pakistan," Farhatullah Babar said in a statement.

India's Supreme Court appealed to Pakistan earlier this month to release the prisoner, Gopal Das, on humanitarian grounds, the Press Trust of India (PTI) reported.

Zardari's move came after Indian Prime Minister Manmohan Singh invited the Pakistani president and prime minister to watch Wednesday's cricket World Cup semi-final between the two countries in Mohali.

Das was sentenced to life in prison in June 1987 and was due to be released by the end of this year, Babar said.

The statement did not say what crime Das had committed but a senior official in Lahore's Kot Lakhpat prison, where he was being held, told AFP that he was jailed on spying charges.

He added that the jail authorities had not yet received release orders for Das.

"The President signed the remission advice in the wee hours of Sunday soon after the invitation of the Indian Prime Minister was accepted," Babar said.

Prime Minister Yousuf Raza Gilani has agreed to visit India to watch the match.

Das's family said they were delighted but stunned by the news.

"We are very happy that he will be joining the family soon...I'm speechless. I have no words to express our happiness," Gopal's brother Anant Vir told PTI.