The al-Shamukh forum, a key al-Qaida propaganda forum, has been taken down by a sophisticated cyberattack, according to media reports.
Cyber security experts say that only a fairly sophisticated attack could have caused the outage as not just the the website, but the server also appeared to be hit by the attack.
Counterterrorism expert Evan Kohlmann said the website used to frequently change servers every few months to escape scrutiny, but so far it was being used by governments to track down al-Qaida.
"These sites can be like spy satellites, they’re great ways of gathering information about your adversaries," he said.
"Bringing them down is like shooting at your own spy satellites. But there are others who don’t agree with that."
The news was first reported by NBC.
Earlier this month, British intelligence MI6, along with officials of the GCHQ, hacked and planted a secret code on an al-Qaida’s website, to divert seekers of bomb making information to a website with recipe for cupcakes.
Reports said that the cyberattack was intended to disrupt efforts by al-Qaida in the Arabian Peninsular to recruit "lone-wolf" terrorists with a new English-language magazine, Inspire.
There are reports that the US backed out of the operation after being involved in the beginning.
