WASHINGTON: The United States said on Tuesday it cannot verify an alleged interview by a Pakistani jailed after he helped the CIA find Osama bin Laden but would be concerned if his torture claims were true.

In May, a Pakistani court sentenced a doctor, Shakeel Afridi, to 33 years in jail after he was arrested following the killing by US troops of bin Laden in May 2011 at his compound in the town of Abbottabad.

Afridi was said to have worked with the CIA to set up a fake vaccination program to obtain DNA samples in Pakistani communities in order to identify relatives of the fugitive al Qaeda leader.

But he was charged and jailed for treason over alleged ties to the militant group Lashkar-i-Islam.

US television channel Fox News said on Tuesday it had obtained an exclusive phone interview with Afridi from behind bars, in which he detailed months of torture by Pakistan's shadowy Inter Service Intelligence.

But doubts were cast on the veracity of the interview, which was released as the United States marked the anniversary of the September 11, 2001 attacks.

Afridi's lawyer said it was a fake, and AFP reporters in Peshawar said a phone conversation would be unlikely as mobile phones are jammed in his jail.

“Frankly, we can't at this point verify the authenticity of the interview,” State Department spokeswoman Victoria Nuland said.

“If we do find that it's authentic though, then the allegations would be extremely concerning. Pakistan obviously has human rights obligations including under the convention against torture.”

“One would expect that the people in the government would be investigating such claims by Dr Alfridi if in fact it turns out that this tape is authentic.”

According to Fox News, Afridi said he had agreed to help the CIA out of love for the United States and said he would do so again despite months of torture by the ISI.

Soon after his arrest he was taken to the ISI headquarters. “My clothes were removed and I was forced by a major to wear old dirty torn rags,” the voice on the suspect recording said.

“It was difficult to eat food. I had to bend down on my knees to eat with only my mouth, like a dog. I sat on the floor.” After being blindfolded for eight months, and shackled in handcuffs behind his back for 12 months, his eyesight and limbs have been damaged, he said.

Nuland said US Secretary of State Hillary Clinton has “been outspoken on this case, has called the sentence unjust, unwarranted and has called for his release.”

Fox News added Afridi's conditions had improved as he is now held in a jail in Peshawar, northwest of Islamabad, where he has a cell with a bed and bathroom and a small gas burner to cook his meals.