The global terrorist group al-Qaida has been studying how to implant explosives into the bodies of suicide bombers, Britain’s Sunday Times reported Sunday.

Western intelligence agencies believe that al-Qaida surgeons are capable of implanting explosive compounds in breasts and abdomens of suicide bombers, which allow bombers to pass security checks at airports. Now the agencies are seeking countermeasures to such a move, the newspaper reported.

The lead doctor was thought to have been killed in a drone attack by the CIA earlier this year. It is reported that he worked with the top bomb-maker for al-Qaida on the Arabian Peninsula (AQAP) Ibrahim al-Asiri. As authorities believe very few doctors are working with Asiri, the CIA is looking for ways of tracking down the group, the newspaper said.

Experts said explosive compounds such as pentaerythritol tetranitrate (PETN) could be surgically implanted in a suicide bomber, and the wounds can be concealed. Also, body scanners in most airports around the world would not be able to detect the installed-bomb, according to the newspaper.

On May 2, U.S. Secretary of Homeland Security Janet Napolitano said the government is watching the every movement of terrorist groups that could explode aircraft with bombs implanted in the human body.