Two members of the audience attending "the most explicit sex show ever staged in Britain" have reportedly had oral sex in an aisle of the theatre.

Tuesday's opening night at Riverside Studios had already caused controversy for featuring some of the most explicit scenes ever seen on a British stage.

The London Evening Standard reported a man in the audience was given oral sex by one of the actresses, although the company, La Fura Dels Baus, later confirmed the man had been a "plant" who used a prosthesis to fake the sex act.

However, on Wednesday night during the performance a woman, who later gave her name as Mistress Poppy, 33, moved into the aisle and performed a sex act with a man.

After the show she insisted she had no connection with the theatre company and that she was a "professional dominatrix" and porn actress. She said: "I've done this sort of thing before, in porn films and live sex shows, and I would have loved to go up on stage and have full sex there too."

Her sexual partner also denied he was taking part in a pre-planned exercise. The 29-year-old German man, who would only give his name as Michael, said: "Everyone in the audience wanted to do what I did."

A Home Office spokeswoman said: "It does not make a difference if it was a member of the cast or a member of the audience who was involved. Sex in public is an offence."

There were no early departures among the audience, who had paid £25 each, the London Evening Standard reports.