Having stood firm for weeks under a barrage of criticism, VeriSign Friday agreed to suspend its controversial SiteFinder service after the Internet's primary governing body issued an ultimatum that it do so or face legal action.

"We will accede to the request while we explore all of our options," VeriSign spokesman Tom Galvin told Reuters News Service.

Earlier in the day, the Internet Corporation for Assigned Names and Numbers (ICANN) informed VeriSign in writing that it had until 9 p.m. Oct. 4 to comply. In that letter, ICANN CEO Paul Twomey says the changes implemented by VeriSign in SiteFinder ''have had a substantial adverse effect . . . on the stability of the Internet.''

ICANN's Security and Stability Advisory Committee is calling for public comments and reports on SiteFinder and has scheduled a "fact-gathering meeting" for Oct. 7 in Washington, D.C. The committee plans later to issue a report on the effects of SiteFinder on the stability of the Internet.

"VeriSign introduced its wild-card service, and although I am told there was some kind of advance notice, it came upon the world as a surprise, and after some hours it became clear that it is a pretty big deal," says Steve Crocker, chairman of ICANN's Security and Stability Advisory Committee. "The preliminary evidence suggests SiteFinder has impacted the stability of the Internet."

VeriSign controls the main database of .com and .net domain names. Last month the company added a wild card to the databases, sending Web users who enter a nonexistent .com or .net address to SiteFinder, a new service that offers Web links and paid advertisements.

SiteFinder has drawn a storm of criticism from technical and commercial fronts. At least two competing Internet companies have sued VeriSign, charging unfair competition. Some anti-spam filters failed when SiteFinder was used, and an uproar among network administrators prompted the Internet Software Consortium to update its DNS software so SiteFinder could be blocked. ISPs are said to have made changes to their networks to bypass the VeriSign service.

"Now you have a warring set of changes and it becomes a rickety system. That makes us engineers nervous. Generally we like to make changes slowly, carefully and with a great deal of consultation," Crocker says.