A Pakistani official said the man, 31-year-old Bilbir Singh, was hanged at dawn.

Army officials say that during interrogation he confessed to links with Indian intelligence.

Pakistan's President Rafiq Tarar: refused petition

Having lost an appeal to a special military court, Mr Singh's sentence was confirmed by the chief of Pakistan's army staff, General Karamat, in April 1998. An army official said Mr Singh was arrested seven years ago, but gave no details of his background, nor the exact charges against him.

He is reported to have been arrested while taking photos of army installations in the town of Okara in Punjab Province.

The prison superintendent said Mr Singh had converted to Islam in the Sahiwal prison and adopted the name of Muhammad Iqbal. He was buried as a Muslim in the prison grounds.

Nuclear tension

Tension between India and Pakistan has increased since both countries exploded nuclear devices last month.

Each frequently accuses the other of acts of spying or sabotage, and are known to hold dozens of each others' nationals on spying charges.

But correspondents say the death sentence on such charges is highly unusual, and an execution is unprecedented.

The execution comes shortly after the Pakistani government accused the Indian intelligence agencies of involvement in bomb attacks in Lahore, Hyderabad and on a train in the province of Sindh.