Cisco Systems issued a statement Monday confirming that police in Sweden have arrested a suspect in connection with the theft of its networking equipment source code last year.

A spokesman for the FBI, which began working on the theft last May, said the case is ongoing and declined to offer details.

The stolen code was a portion of Cisco's Internetworking Operating System version 12.3. The incident has been a matter of concern because malicious hackers might find flaws in the code that could be exploited to impair the functioning of Cisco's routers, which handle a significant portion of traffic on the Internet. At the time of the incident, however, Cisco said that the availability of its code did not pose an increased security risk.

On Tuesday, The New York Times reported that federal officials and security experts have acknowledged that the theft of the Cisco source code was part of a wider pattern of thousands of attacks on military and research computers perpetrated by an unknown number of individuals.

While recently Cisco has been promoting what it calls the Self-Defending Network, its defender in this case has been the network of national and international law-enforcement agencies.

"The FBI fully recognizes the inherent sophistication and global nature of intrusion investigations," the agency said in a statement. "As such, we have worked hard to develop strong partnerships within the international law-enforcement community. In this case, we have been working closely with our international partners to include Sweden, Great Britain, and others. As a result of recent actions, the criminal activity appears to have stopped."

There was more good news for Cisco on Tuesday: The company reported a 16% rise in profits and a sales increase of more than 10% for its third fiscal quarter.