An unspecified amount of the proprietary source code that drives Cisco Systems' networking hardware has appeared on the Internet, the technology giant acknowledged early Monday.

A representative could not confirm, however, that network intruders made off with 800MB of code, as reported by a Russian security group over the weekend.

"Cisco is aware that a potential compromise of its proprietary information occurred and was reported on a public Web site just prior to the weekend," said Jim Brady, a spokesman for the company. "The Cisco information security team is looking into this matter and investigating what happened."

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