China has transferred components and expertise to Iran's weapons of mass destruction and missile programs, officials said. They said some of the Chinese components have arrived via Pakistan, another key ally of Beijing.

"Unacceptable proliferant activity continues," Assistant Secretary of State for Arms Control Stephen Rademaker told the U.S.-China Economic and Security Review Commission on March 10. "We are particularly concerned about continued transfers of CBW- and missile-related technology by Chinese entities to Iran, despite the imposition of sanctions."

The components were said to have included dual-use missile components, raw materials, and expertise to Iran's solid-fuel missile program. Officials said Beijing has also supplied dual-use chemical weapons-related production equipment and technology to Iran.

A key Chinese supplier to Iran has been identified as Q.C. Chen, a Chinese national under U.S. sanctions since 1997. Officials said Beijing has failed to stop Chen, who has sold components to Iran's chemical weapons program.

Another leading Chinese proliferator to Iran and Sudan has been identified as China North Industries Corp., or Norinco. Officials said Beijing has not taken any steps to stop missile and WMD exports by Norinco to the Middle East.

Officials said China has sold major weapons and components to oil-producing countries in the Middle East banned from receiving Western defense systems. They said Beijing has rebuffed U.S. appeals to halt the weapons supplies.

In 2000, Congress formed the commission to investigate and report on national security implications of trade and economic relations between the United States and China. Since 2001, the United States has imposed 60 sanctions on Chinese entities in connection with missile and WMD sales to Iran.

Norinco was said to have supplied advanced weapons systems to Sudan as well as military training to quell the rebellions in the south and in the Darfour province. Norinco was a leading exhibitor at IDEX-2005, which took place in the United Arab Emirates in February.

"Norinco has been particularly active in WMD-related transfers to Iran, resulting in the imposition of U.S. sanctions five times," Rademaker said.

In 2004, China became a member of the Nuclear Suppliers Group and announced the imposition of penalties on two companies that violated Beijing's missile export regulations. China has also pledged to refrain from providing nuclear supplies to any country that does not honor safeguards of the International Atomic Energy Agency.

"China needs to do a consistently better job in identifying and denying risky exports, seeking out potential violators, and stopping problematic exports at the border," Rademaker said. "These issues matter to us because China's success in ending proliferation by Chinese entities is critical to ensuring that weapons of mass destruction do not end up in the hands of terrorists or rogue states prepared to use them."