A senior member of Congress called Thursday for an investigation into deals that US universities are striking with China, amid fears that such tie-ups are compromising academic freedom.

Christopher Smith, who sits on the House of Representatives foreign affairs committee, voiced concern that Beijing-backed "Confucius Institutes" are muting criticism of China's Communist authorities.

"Is American higher education for sale?" said the Republican from New Jersey who also co-chairs the Congressional-Executive Committee on China.

"And if so, are US colleges and universities undermining the principle of academic freedom -- and in the process their credibility -- in exchange for China's education dollars?"

Since 2004, nearly 100 Confucius Institutes have opened on US campuses to promote Chinese language, society and culture.

Most are situated at publicly funded state universities that have otherwise been wrestling with budget cutbacks.

Smith told a hearing on the issue that he will be asking the Government Accountability Office, the independent research unit of the US Congress, to look into the matter.

"We need to look at whether these issues can be handled by the universities, their faculties and trustees themselves or if there is something the US Congress must do to ensure academic freedom is protected," he said.

Perry Link of the University of California in Riverside, who is one of America's best-known sinologists, said Beijing uses Confucius Institutes as an "anodyne approach" to gain a foothold in American higher education.

The teachers that Beijing sends to staff such programs are hand-picked to present the official version of Chinese history and society, Link said.

US college administrators who accept Chinese funding meanwhile implicitly understand that discussions of sensitive issues -- such as Taiwan, Tibet and the Tiananmen crackdown -- are to be avoided, he alleged.

"Money-induced self-censorship prevents even the suggestion of such topics. American students are presented a roseate cameo of China and told that this is the whole," he said in written testimony to the foreign affairs committee.

Thomas Cushman of Wellesley College in Massachusetts said China's quest for formal ties with US colleges was part of a "soft-power" strategy to attain more influence in the West.

He said US colleges have "a moral imperative" to ensure that the benefits of relations with Chinese counterparts don't sideline freedom of expression.