On Monday, The Guardian newspaper said that the CIA organised a fake vaccination programme in the town where it believed Osama bin Laden was hiding in an elaborate attempt to obtain DNA from the fugitive al-Qaida leader's family.
According to the newspaper the bogus vaccination scheme was part of extensive preparations for the raid that killed bin Laden in May.
It has been reported that CIA agents recruited a senior Pakistani doctor to organise the vaccine drive in Abbottabad, and decided to open the "project" in a poorer part of town to make it look more authentic.
The doctor, Shakil Afridi, has since been arrested by the Inter-Services Intelligence agency (ISI) for co-operating with American intelligence agents, the Guardian adds.
Relations between Washington and Islamabad, already severely strained by the bin Laden operation, have deteriorated considerably since then.
Other reports have also emerged, saying that the doctor's arrest had exacerbated these tensions even more as the U.S are concerned for his safety, and probably not very comfortable with him revealing all the details of the scheme to Pakistanis authorities.
The vaccination plan was conceived after American intelligence officers tracked an al-Qaeda courier, known as Abu Ahmad al-Kuwaiti, to what turned out to be bin Laden's Abbottabad compound last summer.
The agency monitored the compound by satellite and surveillance from a local CIA safe house in Abbottabad, but desperately needed confirmation that bin Laden was there before they were allowed to set up the operation without the Pakistani authorities' knowledge.
Sources claim that as DNA from any of the bin Laden children in the compound could be compared with a sample from his sister, who died in Boston in 2010 and provide evidence that the family was present, the fake vaccination programme sounded like a prefect idea.
Moreover, health visitors were among the few people who had gained access to the bin Laden compound in the past, administering polio drops to some of the children.
After agreeing on the details of the plan, American agents allegedly approached Afridi, the health official in charge of Khyber, part of the tribal area that runs along the Afghan border.
The doctor then reportedly went to Abbottabad in March, and claiming that he had found funds for a free vaccination programme for Hepatitis B, paid some low-ranking local government health workers to bypass management officials.
Afridi reportedly even had posters promoting the free programme put all around the city as he attempted to attract the locals and by the same token, the bin Laden's family's attention.
It is now said that Pakistani intelligence became aware of the doctor's activities during the investigation into the US raid in which bin Laden was killed but Islamabad has refused to comment officially on Afridi's arrest and unsurprisingly the CIA also remains tight lipped.
With Pakistan trying to understand the details and tactics used during the American secret operation, it is not surprising for the U.S to be on the defensive, especially as the more details are leaked, the more it will be difficult for American forces in Pakistan to operate under the radar of both the Pakistani authorities and militants and terrorists groups.