Santa Barbara-based Solid Oak Software said it asked Sony Corp., Lenovo Group Ltd., Toshiba Corp. and Acer to not ship personal computers containing anti-pornography software required by China, after claiming the code was stolen from its own product, Bloomberg News reported.

Solid Oak sent cease and desist letters to the four manufacturers this week, Jenna Di Pasquale, a spokeswoman for the company, confirmed to Bloomberg News. The U.S. software maker said earlier it issued similar documents to Hewlett-Packard Co. and Dell, the world’s two biggest PC companies, Bloomberg reported.

By July 1, China will require the “Green Dam” filtering software, authored by a Chinese firm, to ship with all China-bound PCs. A study found significant chunks of Solid Oak’s code in the software.

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