A 24-year-old woman who says she is the prostitute at the center of a Secret Service scandal gave the most complete account yet of her alleged dispute over payment with an agent that led to revelations about nine Secret Service members bringing prostitutes to their rooms on a presidential business trip to Colombia.

In an interview on Caracol News in Cartagena, Dania Suarez said she and some girlfriends had met for a drink April 11 when they encountered an American man out carousing and drinking vodka in a Cartagena bar with other Americans. Appearing composed as she spoke, Suarez said in the interview that she agreed to go back to the agent’s hotel room — not realizing he worked for the Secret Service — and they negotiated ahead of time that he would pay her what she called a “little gift” of $800.

When she asked for the money the next morning, Suarez said, the agent’s pleasant personality from the night before had disappeared and he told her : “Let’s go, b----. I’m not going to pay you.”

She said he pushed her out of his room and into the hallway.

Suarez’s identity could not be independently verified, but many important details of her account appeared to be consistent with versions shared with The Post by people briefed on the incident or involved in the probe.

The interview raised new questions about the conduct of the Secret Service personnel who were in Cartagena preparing for President Obama’s arrival for an international summit, and it drew reaction from congressional figures who are monitoring the agency’s internal investigation.

Rep. Peter King (R-N.Y.), chairman of the House Committee on Homeland Security, said in a statement Friday that he is concerned that the agency has yet to interview two of the 12 women who reportedly spent the night with Secret Service employees, including Suarez.

“I have asked the Secret Service for an explanation of how they have failed to find this woman when the news media seems to have no trouble doing so,” King said.

Secret Service spokesman Edwin Donovan said that the agency has conducted a “comprehensive” investigation that included more than 200 interviews of all 135 Secret Service personnel on the trip, Colombia law enforcement officials, hotel employees and several of the women involved. He said the investigation is complete, but added that the agency would examine any additional information that becomes available.

“If she makes herself available, she’ll be interviewed,” Donovan said of Suarez.

On April 18, the New York Times published an interview with an unidentified woman who offered a similar story to the one Suarez gave to the television station Friday. The woman in the Times story was later identified by other news organizations as Suarez, and she was reported to have left her home in Cartagena and gone into hiding to avoid further media scrutiny.

This week, the Secret Service delivered an update on its investigation to King and other Capitol Hill lawmakers. The agency has chosen to dismiss nine of the 12 employees implicated in the misconduct, while clearing three of serious misbehavior. King said he will ask Director Mark Sullivan for additional information in light of Suarez’s interview and because the agency has now informed him that one of the Secret Service personnel failed a polygraph test. Earlier this week, the agency had said none of the nine employees who had agreed to take the lie detector test had failed.

Hundreds of Secret Service agents were in Cartagena for work, preparing for Obama’s arrival there for an international summit on economic issues. But several were partying hard Wednesday night and into the early hours of Thursday morning before they had to report for assignments in the beach resort town, where prostitution is legal.

The dispute about the payment eventually led Secret Service supervisors to investigate which other agents had brought women to their rooms that night, and to ship a dozen agents out of the country on suspicion they had solicited prostitutes or engaged in other misconduct.

Suarez said that night had been a lot of fun, with the American men she and her friend had met drinking bottle after bottle of vodka. But for her, it was also business. When the agent asked her to come to his room, she said: “I’ll go with you if you give me a little gift At the end I said the little gift is $800.”

She described his response this way: “Okay, baby. Vamonos.”

All that changed Thursday morning, when she was awakened in the agent’s room in the Hotel Caribe at 6:30 a.m. by a hotel desk receptionist, calling to explain it was time for non-paying guests to leave. Suarez said she reminded her client she needed to go and needed her “little gift” of $800.

When he then ejected her from the room, she said she knocked on the door of another agent, with whom her girlfriend had spent the night. Suarez stressed that her friend had liked the other agent and had slept with him without any business transaction.

“She went with him because she liked him, you understand,” Suarez said. “It was not the same as me. . . . For me it was totally business.”

But in the hallway, the client’s friends didn’t seem to care that Suarez had not been paid. She said she sought help from a local police officer, who was supportive, and then said she was going to look for an English-speaking police officer to get the agent to answer the door. She said the agent’s fellow male friends who were in the hallway then begged her not to.

“Please, please. No police, no police,” Suarez said they begged.

“I said in Spanish, ‘Look, if you show no consideration for me, why would I have consideration toward you and not call the police?’ ” Suarez recalled. “In that moment, I felt strong.”

Suarez said the men hustled to pool together some money, gave her $250 and she agreed to leave.

A complaint by the prostitute to the Colombian national police led to a call to the U.S. Embassy, which is required whenever local police have contact with a foreign national, and then a call to the agent’s top supervisor for the region. Paula Reid, a Secret Service supervisor in charge of the Miami office and with oversight of much of South America, launched an investigation that led to the agency shipping a dozen men out of the country before Obama arrived and recommending removing nine members from their jobs.

It wasn’t for two more days before the story exploded on international news that Suarez said she realized who her client worked for.

Staff writer Ed O’Keefe and editor Carlos Lozada contributed to this report.