DULLES, Va. (AP) _ America Online Inc. said Monday it acquired Israel's Mirabilis Ltd., maker of one of the Internet's most popular chat systems, for $287 million.

Mirabilis' chat system, called ICQ (named for the way it sounds: ``I seek you''), is a kind of Internet-based pager that lets users know when their friends are online. The Web-based communications system then allows the users to exchange text-based messages instantaneously. It has more than 12 million registered users worldwide.

AOL, based in Dulles, Virginia, wants to market chat rooms to corporate America as an alternative to phone calls and face-to-face meetings, extending their reach beyond the teens and adults who now use them to communicate.

Under the agreement, AOL will make performance-related payments to Mirabilis of up to $120 million for three years, starting in fiscal 2001.

The acquisition also will boost AOL's momentum in Europe, where its joint venture with Bertelsmann AG is a leading provider of Internet online services. About 60 percent of ICQ's users are based outside the United States and nearly 40 percent are European.