WASHINGTON — The top Democrats on the House and Senate intelligence and judiciary committees have asked the F.B.I. to open investigations into the activities of a Chinese-American woman suspected of trying to sell access to President Trump and his administration.

In a letter to the directors of national intelligence, the F.B.I. and the Secret Service, the Democrats said that recent public reports about the woman, Cindy Yang, raised “serious counterintelligence concerns” about access by foreigners to Mr. Trump’s Florida estate, Mar-a-Lago, as well as criminal concerns about possible human trafficking and campaign finance violations.

[Read the letter to the intelligence chiefs.]

They also asked for access to any information already gathered by the agencies about the extent of Ms. Yang’s contacts with Trump administration officials, security procedures around Mar-a-Lago and whether Ms. Yang or her clients had violated any lobbying laws.

“Although Ms. Yang’s activities may only be those of an unscrupulous actor allegedly selling access to politicians for profit, her activities also could permit adversary governments or their agents access to these same politicians to acquire potential material for blackmail or other even more nefarious purposes,” the Democrats wrote in the letter, dated March 15.