Beijing, China (AHN) - The Chinese government has required firms selling PCs in China to supply, together with the product, a software that blocks access to certain websites effective July 1.

The Chinese-made software called "Green Dam-Youth Escort" should either be pre-installed in the computer or be in a CD, said the notice issued by China's Ministry of Industry and Information Technology on May 19.

The requirement is aimed at blocking pornographic websites to protect children. However, officials of foreign PC makers who tested the software said it can transmit personal information and cause the computer to malfunction and be open to hacking.

Green Dam works by linking computers to a regularly updated database of banned sites. It will then block access to those addresses, said an official who tested the product for a government agency, according to Wsj.com.