A deputy U.S. marshal has been arrested in the UK after he was accused of sexually assaulting a woman on a Delta flight from New York City to London.

The federal marshal, who has not been identified, allegedly ‘acted inappropriately toward at least one woman on board,’ according to law enforcement officials.

The unnamed marshal was one of two who flew from NYC’s John F. Kennedy Airport to London Heathrow Airport on Tuesday to extradite a criminal defendant.

Two law enforcement sources told NBC that the two federal marshals had been drinking during the flight.

The second deputy was also briefly detained and later sent back to the U.S. on Wednesday night without facing any charges, authorities said.

The U.S. Marshals said in a statement that the agency was aware the officer ‘exhibited inappropriate behavior while intoxicated on an inbound flight.’

The agency added that it takes allegations of misconduct by its employees seriously and is cooperating with the investigation by UK law enforcement and other agencies.

‘The U.S. Marshals Service takes seriously any allegations of misconduct by its employees,’ the agency said.

‘The alleged actions of the employees do not reflect the professionalism of the thousands of employees of the USMS or its core values.'”