WASHINGTON (Reuters) - Democratic congressional leaders have asked the FBI to investigate the founder of a Florida massage parlor chain who is an alleged acquaintance of President Donald Trump, according to a letter released on Monday.

House of Representatives Speaker Nancy Pelosi and Senate Democratic Leader Chuck Schumer released the letter, signed by four other lawmakers. It asked investigators to look into “public reports about alleged activities by Ms. Li ‘Cindy’ Yang and her apparent relationship with the president.”

A chain of massage parlors founded by Yang is “suspected of involvement” in human trafficking and prostitution which involves female immigrants being forced to serve as “sex workers,” said the letter to the FBI and other federal investigative agencies.

Senators Mark Warner and Dianne Feinstein and Representatives Adam Schiff and Jerry Nadler signed the letter. It said Yang also reportedly created a business called GY US investments which they allege “may be selling access to the president and members of his family to clients from China.”

Michelle Merson, a Florida lawyer who says she is representing Yang, could not immediately be reached for comment. On a website, Merson posted a video in which she said Yang is scared and in hiding.

Merson said Yang denies the allegations made against her. “Ms. Yang is not concerned because she feels she’s speaking the truth and the truth will free her,” Merson said in the video.

The Democrats’ letter said Yang’s website, which has been taken down, once offered clients the “opportunity to interact” with Trump and other political figures as well as participation in White House and Capitol Hill dinners.

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The letter said that, if proven, such allegations “raise serious counterintelligence concerns.”

It asked if Yang had been the focus of earlier federal or state probes and for an assessment of “counterintelligence risks” which Yang’s activities might have posed.

The Democrats also asked if other individuals have used Mar-a-Lago, the president’s Palm Beach estate, to offer foreigners access to Trump or people around him, as well as whether Yang or her foreign clients have had access to Trump or U.S. officials at the White House, Mar-a-Lago, or other Trump properties.

The FBI had no comment on the legislators’ letter. The White House, the Office of Director of National Intelligence, and the Secret Service did not immediately respond to requests for comment.

Asked about the case, Chinese foreign ministry spokesman Geng Shuang said the Chinese government followed the principle of not interfering in the internal politics of other countries.

“This is what we say and this is what we do,” he told a daily news briefing, without elaborating.