Two Chechen news Web sites collapsed after an alleged coordinated cyber attack from Russian security services

Chechen separatists say Russia's FSB security service is behind the collapse of two Web sites that form a key source of news for the rebel area.

The two sites, www.kavkaz.org and www.chechenpress.com, collapsed under a barrage of attacks from computer hackers just after Russian troops stormed a Moscow theatre killing 41 armed rebels and 128 of the hostages they had been holding there.

"On October 26 ... our Web site kavkaz.org was attacked by a group of hackers," said a spokesman for the US-registered site, run by Movladi Udugov, a former Chechen minister now forced into exile by Russia's second war against separatists.

"We are amazed Russia's special services can operate so freely on US territory," Udugov said.

Udugov's site and Chechen Press, which resumed operations after a few days, have been a valuable source of alternative information for those monitoring the conflict in Chechnya.

Russia's FSB domestic intelligence service declined to comment on what it called the Web sites' "criminal activities".

"They are just lying, they have a tradition of lying, that is their ethic," said FSB spokesman Andrei Larushin.

With most reporters barred from visiting Chechnya, many have used the Web sites for an unofficial angle, admissions of responsibility for rebel attacks or front-line reports.

Albert Digaev, who runs Chechen Press, said a well-coordinated cyber attack had floored his site for several days in the aftermath of the siege.

"Our Web site chechenpress.com was flooded with so-called 'dos-attacks' originated by Russians," he said by email.

Hackers can paralyse Web sites by overloading them with electronic messages, giving them too much data to process.

Udugov said the closure of kavkaz.org was more complex than a mere data overload. He said the registration had been changed against his will, and the site closed.

Web sites are kept on a host computer, but their structure can only be modified by the registered owner.

The Internet host confirmed the registration had been changed. The company was looking into whether it was stolen.

"The site is frozen," Verisign spokesman Brian O'Shaughnessy said. "Currently the site is in dispute."

Udugov moved the site to the new www.kavkazcenter.com address, but by early November that also came under electronic attack and was not working on Thursday.