The suicide bomber who carried out an attack on a United States base in Afghanistan was a Jordanian double agent for al-Qaeda, according to US media reports.

Seven CIA agents and a Jordanian secret agent were killed in the attack. According to various sources the attacker was a doctor who has previously been involved with al-Qaeda, and was working for the Jordanian secret service. He had been sent to Afghanistan to track down key al-Qaeda leaders.

On Wednesday he was admitted to the CIA base because he was said to have important information on al-Qaeda leader al-Zawahiri. Because a Jordanian secret agent vouched for him, he was given virtually no screening.

After the attack, the Taliban claimed it had been carried out by one of their sympathisers, an Afghan soldier.