Following the social media dissemination of a film purportedly showing the activities, Linda De Sousa Abreu, 30, of Fulham, southwest London, was charged on Sunday.
It is said to have occurred on June 26–28 in HMP Wandsworth.
She said nothing when she first appeared in the dock at Uxbridge Magistrates’ Court on Monday other than to confirm her name, residence, and birthdate.
After learning about a video purportedly shot inside the south London jail, police opened an investigation on Friday.
De Sousa Abreu was accused on Saturday with misconduct in public office after being arrested that same day.
According to the charges, De Sousa Abreu engaged in a sexual act with a prisoner in a cell, intentionally and without cause or explanation, and misbehaved in a way that amounted to abusing the public’s trust in the office holder.
She had informed the prison of her trip arrangements when she was arrested at Heathrow Airport, the court heard. She was scheduled to board an aircraft to Madrid.
Portuguese national De Sousa Abreu was given conditional release and is scheduled to appear at Isleworth Crown Court on July 29.