A man in New York has been arrested after he rubbed his crotch against a woman – who turned out to be an undercover police officer.

Felipe Mondragon was aboard the uptown 6 train at 9.05am on 26 October when he rubbed up against the thigh of the plainclothes NYPD officer.

The officer was accompanied by her police sergeant, who was also in plain clothes, as part of an undercover operation.

The Daily News New York reported that the incident happened just as they left Union Square station. The 52-year-old Mondragon was arrested at the next station at 23rd Street.

Mondragon, of Jackson Heights, was revealed to have had two previous arrests on his record, but these were sealed.

He was charged with forcible touching and sex abuse by the officers.

It isn't the first time that such an incident has taken place. In May 2017, Osa Ayanru, 38, was arrested by police at East 59th Street station after he rubbed his crotch on the thigh of plainclothes Detective Jennifer Rosario, again on an uptown 6 train.

Rosario was patrolling the train as part of the NYPD Transit Bureau's Anti-Crime Squad.