Charges by a top activist that New York University dismissed him due to Chinese influence have added fuel to concerns over Beijing's educational clout which critics say hurts US academic freedom.

Chen Guangcheng, one of China's most prominent human rights campaigners who dramatically escaped house arrest last year, has accused the private university of surrendering to "unrelenting pressure" from Beijing.

New York University has adamantly denied the charges and said that it has been generous to Chen -- providing him free education, English lessons, accommodation and family support -- but only planned a one-year fellowship.

But critics note that the university later this year starts operation of a Shanghai campus. Chinese students paying full tuition are highly prized, and New York University is the third largest US recipient of foreign students.

Representative Chris Smith, who heads the House Foreign Affairs subcommittee on human rights, said that New York University controlled Chen's movements and tried to monitor the congressman's conversations with the activist.

"That is not the way you treat a world-class human rights defender who has suffered torture and every other depravation to combat abuse in China. It really is a black mark against NYU," Smith told AFP.

Smith, a Republican from New Jersey, said that US universities faced a "huge systemic problem."

"I have no problem with higher education having a constructive engagement with China as long as you don't gag human rights defenders. Frankly, you should be providing them with space; otherwise, wittingly or unwittingly, you're enabling a dictatorship," he said.

Smith is a passionate opponent of abortion who has campaigned for years against China's one-child-policy. Chen, a self-taught lawyer who has been blind since infancy, exposed widespread forced abortions under the policy.

Chen spent four years in prison before being put under house arrest, where he said that he and his wife suffered severe beatings for daring to keep speaking out.

New York University's supporters said that they wanted to shield Chen, who does not speak English and suddenly moved from house arrest in small-town China to Manhattan, from politics in the United States where abortion is a divisive issue.

New York University professor Jerome Cohen, a leading authority on Chinese law who mentored Chen, said that no political refugee -- "not even Albert Einstein" -- has been treated better by a US academic institution than Chen.

Chen scaled the walls of his home and was driven in a getaway car to the safety of the US embassy on the eve of a visit by then secretary of state Hillary Clinton, setting off a diplomatic showdown.

Harold Koh, who was Clinton's top legal adviser, said that New York University agreed to offer Chen a temporary home "without hesitation, and without concern for any other factor, other than doing the right thing."

Koh, a former dean of Yale Law School, said: "To cast doubt on NYU's generosity now will discourage other universities from taking similarly courageous steps."

Experts said that China's influence on US universities was complicated, with US institutions sensitive to charges of outside pressure but also eager for outside support at a time that traditional funding sources are tight.

The stakes are especially high for foreign scholars of China, who need to publish to advance within academic circles and hence need to ensure visas and access to research in the growing Asian power.

Universities "take great pride in their reputation for academic freedom and freedom of speech," said June Teufel Dreyer, a professor of political science at the University of Miami.

"But like everyone else -- I imagine members of Congress do this, too -- they have a certain amount of integrity, but if it comes to doing just a little bit of a favor for a wealthy contributor, they are not above it," she said.

"Computers always need upgrades, students always need scholarships and you have to repair roofs," she said. "I don't think there's any university, even extremely well-endowed ones, that can't think of a use for a couple of hundred million dollars."

China has set up more than 300 Confucius Institutes around the world, including more than 70 in the United States, to teach students its language and culture.

While an easy source of funding, several universities have seen protests by faculty who believe the institutes will muzzle discussion on sensitive topics for China such as Tibet.

Lionel Jensen of the University of Notre Dame, who has studied Confucius Institutes, said that the close ties to China's government set the institutes apart from institutes run by Britain, France and Germany.

"I don't see any meaningful evidence that academic freedom has been challenged, but it seems ominous to a lot of people that we have an arrangement where these institutes have a virtually autonomous arrangement within the framework of a university," he said.