Two US congressmen blasted the White House and NASA on Wednesday for "dangerous" cooperation with China, saying technology transfer has greatly enhanced Beijing's space and missile capability.

Republican Representative Dana Rohrabacher warned of a ballooning national security threat brought about by what he described as the "overreach" of the White House Office of Science and Technology Policy (OSTP), which was accused of violating legislation aimed at curtailing US-China cooperation.

"China has aggressively sought our technologies through legal and illegal methods for decades," Rohrabacher, chair of the House foreign affairs subcommittee on oversight and investigations, told a hearing.

"Anything that allows China any access to our technology... brings forth some major counterintelligence issues," he said, adding that any US effort "to reach out to the communist Chinese, to engage them on matters of technology, is quite frankly not just naive but dangerous."

Republican Frank Wolf, a major critic of Beijing's human rights policy, told the hearing he was "very troubled with this administration's apparent eagerness to work with China on its space program and willingness to share other sensitive technologies."

He said the considerable US advantage in space has been eroding due to the surprisingly rapid development of China's space program.

Last month, the US Government Accountability Office determined that OSTP violated a statute that prohibits OSTP and US space agency NASA from using federal funds for certain bilateral engagements with China.

OSTP director John Holdren testified that he was told by the Justice Department that the office's activities fell under the president's executive authority to conduct foreign diplomacy, and that the statute therefore did not apply to OSTP.

"I certainly don't dispute technology transfer to China that we did not wish and do not welcome," Holdren said, citing likely leaks from private firms doing business with the Asian giant.

But he defended the scientific engagement with China through several US administrations, saying the cooperation helps in the "effort to get China to change the aspects of its conduct that we oppose," such as on human rights or restrictions to the Chinese market.

Wolf sharply disagreed. "Our engagement with China has not only empowered the government, failed to change their political system and undermined our economic security, it has fueled China's military apparatus," he said, describing China's space program as "led by the People's Liberation Army."

In defending the engagement, Democrat Russ Carnahan described scientific cooperation as "indispensable" for helping advance US diplomatic interests with China.

NASA administrator Charles Bolden, who also testified, said the United States is and intends to remain "the number one space-faring nation in the world."

"Since our engagement with China, Russia or any other nation began, there are no documented cases of transfer of technology that gave technology advantage to any other nation," he said.

Rohrabacher pointed to US technology transfer in the 1990s which helped China improve its missiles and rockets, a development which he labeled "a major disaster" for US national security.

China, which began its manned spaceflight program in 1990 after buying Russian technology, sees its space program as a symbol of its global stature and growing technical expertise.

Hours before the hearing, China completed its first successful docking in Earth orbit, a crucial step towards fulfilling its ambition to set up a manned space station.