A Pakistani doctor who helped the CIA hunt down Osama bin Laden has been convicted of conspiring against the state and sentenced to 33 years in prison.

U.S. officials had urged Pakistan to release the doctor, who ran a vaccination program for the CIA to collect DNA.

The information gathered was used to verify the al-Qaida leader's presence at the compound in the town of Abbottabad where U.S. commandos killed him in May 2011 in a unilateral raid.

The lengthy sentence for Dr. Shakil Afridi will be taken as another sign of Pakistan's defiance of American wishes.

It could give more fuel to critics in the United States that Pakistan — which has yet to arrest anyone for helping shelter bin Laden — should no longer be treated as an ally.

The verdict came days after a NATO summit in Chicago that was overshadowed by tensions between the two countries that are threatening American hopes of an orderly end to the war inAfghanistan and withdrawal of its combat troops by 2014.

Islamabad was invited in expectation it would reopen supply lines for NATO and U.S. troops to Afghanistan it has blocked for nearly six months to protest U.S. airstrikes that killed 24 Pakistani troops on the Afghan border.

But it did not reopen the routes, and instead repeated demands for an apology from Washington for the airstrikes.

Pakistan's treatment of Mr Afridi since his arrest following the bin Laden raid has in many ways symbolised the gulf between Washington and Islamabad.

In the United States and other Western nations, Mr Afridi was viewed as a hero who had helped eliminate the world's most-wanted man.

But Pakistan army and spy chiefs were outraged by the raid, which led to international suspicion that they had been harboring the al-Qaida chief.

In their eyes, Mr Afridi was a traitor who had collaborated with a foreign spy agency in an illegal operation on its soil.

Mr Afridi, who is in his 50s, was detained sometime after the raid, but the start of his trial was never publicised.