Chinese telecoms equipment company Huawei Technologies unlawfully copied Cisco software for one of its products, including the bugs in the program, according to a filing in a US federal court by the world's largest maker of routers, the devices that direct internet communications.

Cisco sued Huawei, the market leader in China, in January. Cisco alleged a pattern of "blatant and systematic copying" of its source code and other materials and infringed several patents that led Huawei to produce routers and other equipment that operate exactly like Cisco's.

Last week, Cisco turned down FBI agents who sought Cisco's co-operation in a criminal investigation. According to FT.com, it is suggested that such an investigation could jeopardise Cisco's trade position with China, although the company did not comment.

Cisco has filed papers in court showing that Huawei tried to recruit Cisco engineers for key projects and asked one Cisco employee to provide detailed information on one Cisco product, according to The Wall Street Journal today.

Cisco is seeking damages and an injunction to block sales of the Chinese company's equipment.

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