Image copyright AP Image caption Dr Shakil Afridi is serving a 23-year jail term

The lawyer for a doctor accused of helping the US find Osama Bin Laden has told the BBC that he has quit the case after receiving frequent death threats.

Lawyer Samiullah Afridi also cited US pressure on Pakistan for the release of Dr Shakil Afridi as another reason for his decision.

Dr Afridi is accused of using the cover of a door-to-door vaccination campaign to help the US find Bin Laden.

Pakistan was not informed of the 2011 raid which killed the al-Qaeda leader.

Samiullah Afridi told the BBC that his life had been under threat since he took up the case two years ago.

Mr Afridi - who is not related to Dr Afridi - said he had left the country at one point because of safety fears.

He said that militants had now given him a deadline to choose the "right way", by which they meant to leave the case.

"I took the case on humanitarian grounds, but now I have to look for my own life, it is more important," he said.

He also said US pressure on Pakistan to release the doctor was "inappropriate" and was hindering the case.

In addition, he said Washington's continued refusal to release Dr Aafia Siddiqui - a US citizen of Pakistani origin jailed for alleged links to al-Qaeda - was also "creating hurdles".

Mr Afridi, one of four lawyers representing the doctor, said he had "no option" but to quit the case.

US pressure

Dr Shakil Afridi was convicted of alleged ties to militant groups and sentenced to 33 years in jail by a tribal court in 2012.

The sentence was widely seen as punishment for his alleged role in the Bin Laden raid, which he denies.

His jail term was reduced by 10 years by a court in Peshawar earlier this year, after pressure from the US and the doctor's relatives.

However, he still faces a separate trial in which he is explicitly accused of colluding with the CIA.

US special forces entered Bin Laden's compound in Abbottabad and shot him before flying the body out of Pakistan and burying it at sea.

The raid was acutely embarrassing for Pakistan and the episode plunged relations with Washington to a new low.