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.

US officials had urged Pakistan to release the doctor, who ran a vaccination programme for the CIA to collect DNA.

The information gathered was used to verify the al-Qaeda leader's presence at the compound in the town of Abbottabad, where US 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 US wishes.

It could give more fuel to critics in the US 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.

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

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

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

In the US and other Western nations, Afridi was viewed as a hero who helped eliminate the world's most wanted man.

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

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

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