A group of Stanford University professors has asked the Justice Department to stop looking for Chinese spies at US universities, joining an effort by human rights groups to end a Trump administration programme they said caused racial profiling and was terrorising some scientists.

The "China Initiative" launched in late 2018 aimed to prevent US technology theft by China but has since "deviated significantly from its claimed mission", according to the September 8 letter, which was signed by 177 Stanford faculty members and made public by them on Monday.

"[It] is harming the United States' research and technology competitiveness and it is fuelling biases that, in turn, raise concerns about racial profiling," the letter said.

Asked about criticism of the China Initiative, Justice Department spokesperson Wyn Hornbuckle said the government was "dedicated to countering unlawful [Chinese] government efforts to undermine America's national security and harm our economy," while acknowledging the threat of hate crimes against Asian Americans. "We take seriously concerns about discrimination," he said.

The Justice Department has published details of at least 27 cases related to the initiative, with results including some guilty pleas, some cases dropped and some ongoing.

Professors at Massachusetts Institute of Technology and Harvard University were among those charged, as were five Chinese scientists who were visiting scholars last year — although those charges were dropped in July.

On Thursday, a federal judge in Tennessee acquitted a professor accused of hiding Chinese ties in his Nasa research grant application, saying prosecutors failed to provide evidence he intended to defraud the government.

"I think what the FBI's done in most cases is to scare people — investigating people and interrogating them. And it's harmful to the country," said Peter Michelson, Stanford's senior associate dean for the natural sciences, an organiser of the letter.

Another organiser, Stanford physicist Steven Kivelson said he got involved because he saw his colleagues of Chinese origin suffered from the hostile environment they were subjected to due to the initiative.

Former US Energy Secretary and Nobel prize winner Steven Chu, a professor at Stanford, said that rather than help protect US advantages in technology and understanding, the programme risked undermining America's lead in science.

"We were the brain gain for half a century," he told Reuters in an interview. "You really want to throw this away?"