PESHAWAR (REUTERS) - A Pakistani lawyer under death threats for defending a doctor who helped CIA agents hunt Al-Qaeda leader Osama bin Laden was shot dead on Tuesday, police said, and a Taleban splinter group claimed responsibility.

Samiullah Afridi represented Dr Shakil Afridi, who was jailed in 2012 for 33 years for running a fake vaccination campaign believed to have helped the US intelligence agency track down bin Laden.

That sentence was overturned in 2013 and the doctor is now in jail awaiting a new trial.

Samiullah Afridi was shot dead on Tuesday as he was returning to his home in the northwestern city of Peshawar, police said.

According to local media, he had recently returned there from abroad after leaving Pakistan for his safety.

The Pakistan militant group Jundullah, a splinter group of the Taleban, claimed responsibility.

"We killed him because he was defending Shakil, who is our enemy," spokesman Fahad Marwat told reporters.

US officials have hailed Shakil Afridi as a hero for helping pinpoint bin Laden's location before a 2011 raid by US special forces in Abbottabad, Pakistan, that killed the Al-Qaeda leader after more than a decade of searching for him.

Samiullah Afridi stopped representing the doctor last year, saying he had become a target.

"I have been receiving threats from various organisations, and because of those threats I even went to Dubai some time back," he told Reuters TV.

"Some organisations do not want us to continue defending this case... Not only is my life in danger, my family is also in danger. I have, therefore, decided to quit this case."

Shakil Afridi's original sentence damaged ties between Pakistan and the United States that were already strained over the bin Laden raid.

Angry US senators withheld US$33 million in aid from Pakistan in retaliation.