The Jordanian doctor who killed seven CIA operatives in a suicide bombing in Afghanistan was about to be searched only moments before the attack, the CIA's chief revealed Saturday.

Although the CIA had been working with bomber Humam Khalil Abu Mulal al-Balawi as a potential intelligence asset against al Qaeda prior to the Dec. 30 attack, it now appears he had been working as a double agent against the U.S.

CIA Director Leon Panetta, writing in the Washington Post, said the agency considered the potential for danger that al-Balawi posed, even as officials planned intelligence meetings with him.

Panetta's revelation comes as new video footage surfaced Saturday in which the bomber speaks about avenging the death of a former Pakistani Taliban chief Baitullah Mehsud, who was killed by a CIA missile in August.

In the video, the 32-year-old al-Balawi says that all jihadists should avenge Mehsud's death by attacking U.S. targets.

"We will never forget the blood of our emir Baitullah Mehsud," says al-Balawi, wearing an Afghan dress during the 90-second video.

"We will always demand revenge for him inside America and outside. It is an obligation of the emigrants who were welcomed by the emir."

The clip, which was shown on the al-Jazeera news network and on Pakistani television, purportedly shows al-Balawi sitting with Mehsud's successor and new Pakistani Taliban chief, Hakimullah Mehsud.

The video also confirms the Pakistani Taliban's claim of responsibility for suicide attack, which is among the deadliest in CIA history.

Ties to two terror groups

The bombing took place after al-Balawi was brought into the CIA's headquarters in the eastern Afghan province of Khost under the premise that he had information about Ayman al-Zawahri, al-Qaeda's second-in-command.

The video also confirms that al-Balawi had ties to both the Taliban and al Qaeda, in addition to contacts within the Jordanian and U.S. intelligence communities.

But during the video, al-Balawi belittles his U.S. contacts and pledges his allegiance to jihad.

"The emigrant for the sake of God will not put his religion on the bargaining table and will not sell his religion even if they put the sun in his right hand and the moon in his left," he said, referencing a verse in the Qur'an.

The video is unusual because the Pakistani Taliban doesn't usually take responsibility for attacks in neighbouring Afghanistan.

The evidence could lead to increasing military action in the rugged tribal regions of Pakistan, long considered to be a staging ground for militant attacks on NATO targets in Afghanistan.

In Jordan, al-Balawi's father confirmed that it was in fact his son speaking in the video.

"He was very opposed to what was happening in Iraq, the occupation of Palestine and the killings of Muslims in Afghanistan," Khalil Abu Mulal al-Balawi told The Associated Press.

"We knew he was very zealous for God and his religion."

With files from The Associated Press