Columbus police had accused Stormy Daniels of committing a misdemeanour sex offence

Ohio police officers were politically motivated when they arrested Stormy Daniels, the porn star who has described having an affair with President Donald Trump, at a strip club last year, the actress said in a lawsuit on Monday.

The Columbus vice unit officers who arrested Daniels on July 12, 2018, were registered Republicans as is the president, Daniels, whose real name is Stephanie Clifford, said in her lawsuit filed in federal court in Ohio.

"Defendant officers believed that Ms. Clifford was damaging President Trump and they thereafter entered into a conspiracy to arrest her during her performance in Columbus in retaliation for the public statements she had made regarding (Trump)," the suit said.

The legal action against the officers could bring to light further details about the circumstances of Daniels' arrest, which made headlines at the time.

Columbus police had accused Daniels of committing a misdemeanour sex offence while performing at the club Sirens by touching three customers who were undercover vice detectives.

The charge was dropped hours later. Daniels had committed no crime because she did not perform regularly at the club, as required under the law, a city attorney said at the time.

The Columbus Division of Police launched an internal investigation soon after the incident.

"The Columbus Division of Police internal affairs bureau continues its investigation, therefore it would be inappropriate for us to comment on this matter at this time," the division said in a statement about the lawsuit.

The division, in Ohio's state capital, was not named as a defendant in Daniels' lawsuit, which accused the officers of violating her civil rights.

A representative for the police union for the officers could not immediately be reached for comment.

Daniels sued Trump for defamation in March 2018, before her arrest, and was seeking release from a non-disclosure agreement she signed before the 2016 presidential election to remain silent about the affair she said she had with Trump.

Trump has denied having an affair with Daniels, saying she was paid to stop "false and extortionist accusations."

A federal judge in Los Angeles dismissed Daniels' defamation lawsuit last year.

Daniels' attorney, Michael Avenatti, has described her arrest as a politically motivated set-up since the day it happened.

"Here in America, unlike in Russia, we don't arrest citizens for political purposes in order to silence them," Avenatti said in a statement on Monday.