After six cancer researchers were removed from their posts at Moffitt Cancer Center in Florida last December accused of having secret ties to a medical university in China, some Republican senators warned of possible spying operations around sensitive research.

Sen. Marco Rubio (R-Fla.) and Rick Scott, (R-Fla.) indicated in a letter signed by Sen. Tom Cotton (R-Ark.) that U.S. universities, companies, and hospitals should pay attention and “be proactive about this risk,” according to the Washington Examiner.

As the Examiner indicated, the senators issued the warning after the scandal in which six researchers were implicated for secretly participating in a program considered by federal agencies as an unconventional Chinese intelligence gathering operation.

According to the Tampa Bay Times, Moffitt’s internal compliance office conducted an internal investigation into any ties or associations the hospital had with any Chinese investigative arm, finding several “compliance violations.”

Most of the violations involved Moffitt employees participating in China’s Thousand Talents program, which was designed to recruit researchers and other experts from U.S. and European universities and companies.

On Jan. 17, Moffitt officials argued that none of the faculty who had participated in the Talents program had adequately or timely disclosed the full extent of their activities in the program before initiating investigations with Moffitt.

Of that, Moffitt-affiliated faculty “acknowledged receiving personal payments that they did not promptly disclose to Moffitt,” and further “acknowledged having opened or maintained personal bank accounts in China to receive Talents program compensation,” Science magazine reported.

“We should all be very concerned about the threat of Communist China and its attempts to steal U.S. research and intellectual property,” the three senators said in a statement sent on Friday to Richard Pollard, president of the American Hospital Association.

According to the Washington Examiner, the controversy involving a Chinese American researcher who recruited the CEO and president of the H. Lee Moffitt Alan List Cancer Center and Research Institute and three other colleagues to be part of the program that sought top-level scientists and talent involved paying thousands of dollars to participants, without disclosing the contracts to the employer.

Timothy Adams, Moffitt board president and former speaker of the Florida House, said the institution had done its job, arguing that it had heeded the call of the National Institutes of Health—which is in charge of the research—to proactively review and act on the issue.

Another agency working to strengthen enforcement of the rule against medical research funding and grant proposals is the FBI.

According to the Tampa Bay Times, since 2008 Moffitt has worked closely with Tianjin Medical University to develop research projects.