In a statement on its website, the ministry, without naming the companies, said one was a trading firm based in the eastern province of Jiangsu and the other a chemical firm based in the eastern province of Shandong.

The ministry did not provide details on the products nor to which countries they were exported.

"The Chinese government always has fought against the proliferation of weapons of mass destruction and anti-terrorism, and has launched a series of rules controlling the export of nuclear, biological and chemical weapons and missiles," it said.

To China's dismay, the United States has in recent years repeatedly sanctioned Chinese companies for proliferating missile technology or other technologies used to build weapons of mass destruction.

In September 2003, Washington imposed sanctions on the government and state-run weapons maker China North Industries Incorporated (NORINCO) for allegedly selling advanced missile technology to an unnamed country.

In July 2003, the United States slapped sanctions on NORINCO and China Precision Machinery Import-Export Corporation (CPMIEC) for allegedly supplying missile technology to Iran and another unnamed country.

Penalties were also imposed on the Taian Foreign Trade General Corporation of China, the Zibo Chemical Equipment Plant of China and the Liyang Yunlong Chemical Equipment Group Company in July 2003 for also allegedly supplying missile technology to Iran.

The Zibo chemical company and the Taian trading company are in Shandong while the Liyang Yunlong company is based in Jiangsu.

WAR.WIRE