The chairman of the House Committee on Homeland Security said the evidence was uncovered by Secret Service investigators who are seeking to question the women, The New York Times reported.
King said additional Secret Service personnel have been sent to Colombia to conduct the interviews.
The New York Republican, who was briefed on the investigation by Secret Service head Mark Sullivan, said the picture of what transpired in Cartagena remains incomplete.
"The 11 agents are having different recollections about what happened or are not telling the truth," King said.
The Pentagon is moving forward with its own investigation after learning several -- perhaps 10-12 -- military service members also were involved.
Sen. Susan Collins, R-Maine, the ranking minority member of the Homeland Security Committee, who was also briefed by Sullivan, said about 20 women were brought into the hotel, and some of them ended up with military personnel, the Times said.
"Could they have planted bugs, disabled weapons, or in any other ways jeopardized security of the president or our country?' Collins said she had asked the Secret Service. "Is there any evidence of previous misconduct by these or any other agents on other missions?"
ABC News reported earlier Secret Service agents also had gotten into a dispute with bouncers at an upmarket Colombian brothel, an incident that drew local police.
Witnesses told ABC the agents also boasted at the Pley Club in Cartagena about their mission. They allegedly made remarks like "We work for Obama" and "We're here to protect him."
The 11 agents arrived in Cartagena two days before the president, who attended the Summit of the Americas last weekend.
They reportedly visited the Pley Club, one of Colombia's best-known brothels, Wednesday night.
Prostitution is legal in Colombia.
Witnesses said some of the agents sought the services of the highest-category prostitutes at the club, who charge at least $200. While they paid in advance, there was a later dispute about the bill in which club bouncers got involved.
The security clearances of the 11 agents have been suspended while the charges are being investigated, CNN reported.