Claudia Trevisan had travelled to Yale University in the hope of securing an interview with the president of Brazil's supreme court. Instead, she found herself writing a very different legal story. Soon after arriving on campus she was arrested, handcuffed and held in a cell for several hours.

In an interview with the Guardian, the 48-year-old correspondent for O Estado de S Paulo accused university police of "extremely violent and disproportionate" behaviour after she was detained for alleged trespassing at the New Haven, Connecticut, campus on Thursday.

Trevisan said that after arriving on campus in the afternoon she asked around to find out the location of a seminar featuring Joaquim Barbosa, who is a high-profile minister pursuing corruption cases in Brazil.

She said that she entered a concert hall building near Yale law school to seek confirmation that Barbosa was inside, with the intention of waiting on the street in the hope of making contact with him after the event.

Then, according to her account, a police officer began asking questions and confiscated her passport, telling her he knew who she was and that she had been repeatedly warned she did not have permission to be there.

She was then arrested and taken to a police station in New Haven, where she was kept in a cell in difficult conditions for about three and a half hours, photographed and fingerprinted.

Trevisan said that she had spoken on the phone earlier in the day with Barbosa, who had declined her interview request, and also been informed by Yale law school's communications director that the event was not open to the media.

However, since she was already en route to Yale from her base in Washington, DC she decided to go anyway on the off chance that he would change his mind.

Trevisan admitted that she did not initially identify herself as a journalist when challenged, but said there was nothing to suggest that she had no right to enter the building and that she did not believe she was breaking the law.

"It's not that I broke in or that I entered without saying what I'm looking for," she said. "It was totally disproportionate. I was already going out of the building … I was handcuffed, treated like a criminal, it was totally shocking. For me it was hard to understand and totally unnecessary. It's violence against a journalist trying to do her work."

Yale University said in a statement that it does not plan to file charges.

"Before she came to the Yale campus on September 26 to attempt to interview Justice Barbosa, Ms Cláudia Trevisan was told that the Global Constitutionalism Seminar attended by Justice Barbosa was a private event closed to the public and the media, and that she was not permitted on Yale property," the statement said.

"She came onto Yale property, entered the law school without permission, and proceeded to enter another building where the attendees of the seminar were meeting. When asked why she was in the building, she stated that she was looking for a friend she was supposed to meet. She was arrested for trespassing. The police followed normal procedures and Ms Trevisan was not mistreated in any way.

"Although the arrest for trespass was justified, the university does not plan to pursue the charge with the local prosecutor. The law school and Yale University accommodate hundreds of journalists in the course of a year at public campus events and for interviews with members of the Yale community and visitors. As with all journalists, Ms Trevisan is welcome to attend any public event at Yale and speak with anyone who wishes to grant her an interview."

The newspaper has sent a letter to Yale protesting against her treatment, Trevisan said. She has only been in the US for a month. "I was in China for five years and never in China did something like this happen to me," she said.