Cisco Systems Inc. (CSCO) said on Tuesday authorities in Sweden had detained a person for stealing its source code, the basic instructions for the machines that direct Internet traffic around the globe.

"We are aware that a person has been detained in Sweden related to the IOS source code theft and are encouraged by this action," the San Jose, Calif., company said in a statement.

Swedish police have declined to say whether their investigation of a 16-year-old boy May 2004 incident that exposed the inner workings of Cisco's Internetworking Operating System, or IOS.

Police in Uppsala, a university town north of Stockholm, said on Tuesday they had been contacted by the Federal Bureau of Investigation (search) about a teenager already in trouble with the law in Sweden for allegedly hacking into university computers.

Swedish police said the teenager, whom they would not identify by name, had been questioned about hacker attacks on Uppsala University computers, but had not been arrested.

"We have not received any formal request from (U.S. authorities) to question or apprehend the 16-year-old," Uppsala police spokesman Christer Nordstrom said. "But I can confirm that there has been an exchange of information with the FBI."

The New York Times reported that the Cisco (search) theft was part of a broader hacking campaign that targeted computer systems run by U.S. universities and government agencies.

Several supercomputer labs in April 2004 reported that computers connected to the high-speed TeraGrid (search) network had been breached.

A spokeswoman for the White Sands Missile Range (search) in New Mexico confirmed that the facility had experienced an intrusion around the time that Cisco reported its breach, but said no sensitive information was obtained.

"Basically, they got into some local weather forecasts," spokeswoman Monte Marlin said.

Source code, the underlying blueprint of computer software, determines how programs work. Companies like Microsoft Corp. (MSFT) zealously guard their source code because they consider it the lifeblood of their business.

Cisco said last May that portions of its IOS source code had been copied from its internal systems and posted on a foreign Web site for several days, where presumably other hackers could examine it closely for security flaws. The company said at the time that the breach would not put customers' equipment at risk.

The FBI said in a statement it had been working with authorities in Sweden and Great Britain to track down the culprit. "As a result of recent actions, the criminal activity appears to have stopped," it said.

Authorities in Great Britain arrested a 20-year-old man last September in connection with the Cisco hacking, but no charges have been filed.