(CNN) -- The man identified as the double agent who killed eight people at a U.S. base in Afghanistan was a Jordanian doctor recruited as a counterterrorism intelligence source, a senior Jordanian official said Tuesday.
A former U.S. intelligence official identified the suicide bomber Monday as Humam Khalil Abu-Mulal al-Balawi.
The Jordanian official, speaking on condition of anonymity, said authorities in Jordan arrested al-Balawi more than a year ago "for some suspicious information related to him" but released him because of a lack of evidence.
"After few months, he got in touch with us through the Internet and sent us several e-mails that include very important and rather dangerous information that might affect the security and stability of the country," the official said.
"We kept in touch with him through e-mails in order to get more information and also trying to bring him over to be able to get more information. We shared and exchanged the information he gave us with some other friendly countries that are involved in countering terrorism."
The official said Jordan could not confirm that al-Balawi was the bomber, "because we are not on the ground."
"But we are not denying that if he is the one, then he is the Jordanian doctor," the official said.
The December 30 blast at a U.S. base in Khost, in southeastern Afghanistan, killed seven CIA operatives including two from private security firm Xe, formerly known as Blackwater. The eighth victim was Jordanian Army Capt. Sharif Ali bin Zeid, a cousin of Jordan's King Abdullah II.
U.S. sources said bin Zeid was the Jordanian operative working closely with al-Balawi, who was from the same hometown as the onetime leader of al Qaeda in Iraq, Abu Musab al-Zarqawi.
Jordanian and U.S. intelligence agencies apparently believed that al-Balawi had been rehabilitated from his extremist views and were using him to hunt Ayman al-Zawahiri, al Qaeda's No. 2 figure, the former intelligence official said.
In a posting on its Web site last week, the Taliban in Afghanistan claimed that the bomber was an Afghan National Army soldier.
On Sunday, however, Pakistani Taliban chief Hakimullah Mehsud said in an e-mail that his arm of the Islamic movement carried out the attack, using a Jordanian national. Mehsud's message predicted, "This will be admitted by the CIA and the Jordanian government."
The attack was "a huge blow, symbolically and tactically," because it eliminated such a large number of CIA officers, who can require years to become ingrained in the region, said Reva Bhalla, director of analysis for the international intelligence firm STRATFOR. In addition, the attack showed the ability of the Taliban to penetrate perhaps the most difficult of targets: a CIA base, she said.
Former CIA official Robert Richer called it the greatest loss of life for the agency since the 1983 bombing of the U.S. Embassy in Beirut, Lebanon, which killed eight agents. An American intelligence official vowed last week that the United States would avenge the attack.