Rebecca Blake, 29, and Conor McRedmond were arrested after an all-day drinking binge.
They were held for five days and accused of having sex outside marriage and being drunk in a public place – both criminal offences in the strict Islamic state.
Miss Blake, a recruitment consultant, met Irishman Mr McRedmond at The Irish Village, a hotel bar where patrons pay £10 a head for an all-you-can-drink brunch event. After drinking for 12 hours, the pair hailed a cab towards Dubai Marina.
Minutes later they were spotted in a passionate embrace by the driver in his rear view mirror, according to police reports.
Incensed by their behaviour, the driver stopped and complained to police in a patrol car parked nearby. When he returned with an officer, they saw Miss Blake having sex on the back seat of the cab with Mr McRedmond, it is alleged.
A source said: ‘They were completely drunk, started kissing and then got carried away. That’s when they started having sex.
‘When the police officer went over, he found the woman was completely naked and they were having sex on the back seat.’
Miss Blake works for global recruitment firm Manpower in Dubai. She is from Croydon, South London, and was educated at her local Catholic high school.