Washington: By providing nuclear and missile technology to countries like Iran and Pakistan, China is increasing the proliferation of weapons of mass destruction, a Congressional report has said.

The report further said that such activities have continued to raise questions about China's commitment to non-proliferation and a need for US sanctions.

"China has taken some measures to mollify US and other foreign concerns about its role in weapons' proliferation.Moreover ,supplies from China have aggravated trends that result in ambiguous technical aid, more indigenous capabilities, longer-range missiles and secondary (re-transferred) proliferation," the Congressional Research Service (CRS), said in a report to the lawmakers.

According to unclassified intelligence reports submitted to Congress, China has been a "key supplier of technology, particularly PRC (People's Republic of China) entities providing nuclear and missile-related technology to Pakistan and Iran," said CRS report.

CRS is an independent research wing of the US Congress and prepares internal reports for US lawmakers on issues of their interest.

"PRC proliferation activities have continued to raise questions about China's commitment to non-proliferation and a need for US sanctions," said the report. The previous Bush Administration imposed sanctions on 20 occasions on various PRC "entities" (including state-owned entities) for troublesome transfers related to missiles and chemical weapons to Pakistan, Iran, or perhaps another country, including repeated sanctions on some "serial proliferators."

"Skeptics question whether China's cooperation in weapons' non-proliferation warrants the US pursuit of closer ties, even as sanctions were required against PRC technology transfers. Some criticise the imposition of US sanctions targeting PRC "entities" but not the government. Others doubt the effectiveness of any stress on sanctions over diplomacy," the report said.

Among those sanctions, in September 2001, the Administration imposed missile proliferation sanctions that effectively denied satellite exports after a PRC company transferred technology to Pakistan, despite the promise of 2000.

In September 2003, the State Department imposed additional sanctions on NORINCO, a defence industrial entity, effectively denying satellite exports to China. However, for six times, the State Department waived this sanction for the ban on imports of other PRC government products related to missiles, space systems, electronics, and military aircraft and issued a permanent waiver in 2007.

Since 2009, the Obama Administration has imposed sanctions on six occasions on multiple PRC entities for missile or other weapon's proliferation, the report said.