The SCO Group has targeted two US government agencies in an escalation of its campaign to assert and protect its rights in the UNIX operating system, parts of which the software company claims were illegally copied into the Linux source code.

CNET News.com reports that the Department of Energy's Lawrence Livermore National Laboratory (LLNL) and the National Energy Research Scientific Computing Centre (NERSC) both received letters from the company urging them to buy SCO's UnixWare license scheme or run the risk of legal action.

SCO has been waging war against what it sees as rampant copyright infringement of its rights in UNIX. It is suing IBM for letting parts of UNIX 'slip' into Linux and this month sued two Linux end-users, AutoZone, a Fortune 500 car parts retailer, and DaimlerChrysler, alleging that their use of Linux is in breach of SCO's copyright.

The end-user actions had been anticipated following letters that were sent to 6,000 of SCO's existing licensees in December, requesting confirmation that they were not in breach of their licence agreements.

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