A Pakistani doctor who helped the U.S. track down Osama bin Laden has been convicted of high treason and sentenced to 33 years in prison, Belfast Telegraph reported.

Shakil Afridi was also ordered to pay a fine of about 3,500 U.S. dollars (£2,200), said government official Nasir Khan.

If Afridi does not pay, he will spend another three and half years in prison.

Mr Khan is a government official in Pakistan's Khyber tribal area, where Afridi was tried.

Afridi ran a vaccination programme for the CIA to collect DNA and verify bin Laden's presence at the compound in the town of Abbottabad, where he was killed last May by U.S. commandos.

U.S. secretary of state Hillary Clinton has called for Afridi to be released, saying his work served Pakistani and American interests.

Afridi was detained some time after the raid on May 2 last year, but the start of his trial was never publicised.

"He was working for a foreign spy agency. We are looking after our national interests," said a Pakistani intelligence official.

The U.S. operation that killed bin Laden severely strained ties with Pakistan. The Pakistani government kicked out U.S. military trainers and limited counter-terrorism co-operation with the CIA.

The relationship got worse in November when the U.S. killed 24 Pakistani soldiers at two posts along the Afghan border, an attack that Washington said was an accident but the Pakistani army insisted was deliberate.