A double agent who killed seven CIA officers in Afghanistan sent a plea to Islamist writers a few weeks earlier urging them to launch suicide attacks, the SITE Intelligence monitoring group said, citing a militant forum.

The agent, Humam Khalil Abu Mulal al-Balawi, himself a former prolific writer on pro-al Qaeda Internet forums, urged fellow propagandists "nearly 50 days ago" to come to the "battlefield," SITE reported an associate of Balawi's as saying.

"Beware, beware that you are satisfied with writing on the forums without going to the battlefield in the Cause of Allah," a January 10 posting on the al-Fallujah forum by the associate, Abu Kandahar, quoted Balawi as saying.

"Running away from hell-fire and gaining paradise is a personal matter that concerns only you. I see no path to this except for death in the Cause of Allah."

Balawi blew himself up on December 30 inside Forward Operating Base Chapman, a well-fortified U.S. compound in Khost province in southeast Afghanistan, killing seven CIA officers and a Jordanian intelligence officer.

The attack was the second-most deadly in CIA history.

Worries about radicalization and militant propaganda over the Internet have grown rapidly in the West following the December 30 attack, a botched December 25 airliner attack by a Nigerian Islamist and the November 5 killing of 13 people at a U.S. army base in Texas by a gunman linked to a Yemen-based preacher.

Balawi, a Jordanian double agent, was also the author under the pen name Abu Dujana al Khorasani of some of the most celebrated anti-Western commentaries on the Internet.

Former intelligence officials have said Balawi was recruited by Jordanian spies to infiltrate al Qaeda and the Taliban.

Balawi had associated with Islamists in the past, but U.S. and Jordanian spy agencies believed, incorrectly, that he had been successfully "de-radicalized" and saw his involvement with websites as cover, security analysts have said.

Abu Kandahar said without elaborating that Balawi had sent the appeal while he was in "the battlefields of glory."

Abu Kandahar suggested he approved of Balawi's appeal, sent to the administrators of the al-Fallujah forum, a network used by al Qaeda supporters and sympathizers, because propaganda was only credible if backed by action.

"Writers can create something big, but under one condition: They die so that their thoughts can live," Anbu Kandahar was quoted as saying. "Do not forget his will and go on his path."

LONDON (Reuters)