Prime Minister Imran Khan has offered to release jailed Pakistani surgeon Shakeel Afridi, who helped the CIA track down al-Qaeda chief Osama bin Laden, in exchange of neuroscientist Aafia Siddiqui serving an 86-year US prison sentence after her 2010 conviction in shooting at FBI agents and American soldiers in Afghanistan.

Khan, who is visiting Washington on his maiden official trip, in an interview to Fox News appeared reluctant to give any commitment on the release of Pakistani doctor Afridi.

He said that the release of Afridi is an "emotive issue" for the country as in Pakistan he is considered a spy for the US.

He, however, said he would be willing to consider releasing Afridi in exchange for Pakistani neuroscientist Aafia.

“So, we could negotiate some sort of swap,” Khan said, adding that this was not talked about during his meeting with President Donald Trump in the White House.

The negotiations for swap of Afridi and Siddiqui could take place in the future, he said. “We can negotiate. I mean, no negotiations have started,” Khan told US President Donald Trump's favourite news channel.

Afridi, a 57-year-old former surgeon of Khyber Agency, had run a false vaccination campaign in the Pakistani garrison city of Abbottabad to help the CIA track down Osama, who was then killed in a covert US raid on May 2, 2011. Afridi was arrested from Peshawar later that year.

Initially, he was accused of organising a fake immunisation campaign for the CIA to confirm presence of Osama but later awarded 33 years sentence on multiple charges of anti-state activities, including extending support to militant outfits. His sentence was later reduced to 23 years.

The US has been demanding Pakistan to release Afridi.

The issue of Afridi's release is reportedly one of the major obstacles to the improvement of ties between the US and Pakistan. The US State Department has previously said that Afridi has been unjustly imprisoned in Pakistan and Washington has clearly communicated its position to Islamabad in his case, both in public and in private.

Pakistani neuroscientist Aafia, who was convicted in 2010 on charges of attempted murder and assault of US personnel, is serving an 86-year sentence at the Federal Medical Centre, Carswell in Fort Worth, Texas.

A court in New York sentenced Aafia, an MIT graduate, on September 23, 2010.

The sympathisers of the 47-year-old claim that she was arrested in Pakistan and handed over to intelligence agencies who then transferred her into US custody. Both US and Pakistani officials, however, say that she was arrested in Afghanistan.

Aafia allegedly went missing for five years before she was discovered in Afghanistan. It is said that she snatched a gun during interrogation in Ghazni and tried to shoot a US soldier. She has also been accused of working for Al Qaeda.

During his election campaign, Khan had said if elected he would make efforts to repatriate Aafia and other Pakistani prisoners serving jail term in foreign countries.