George Rekers, the American anti-gay campaigner photographed returning from holiday with a male prostitute, has resigned from the board of the National Association for Research and Therapy of Homosexuality (NARTH), the country’s more prominent gay cure organisation.

Professor Rekers, a 61-year-old Baptist minister who believes homosexuality can be cured, was photographed returning from a ten-day European holiday with a 20-year-old male escort known only as Lucien.

He denied any “illegal or sexual behaviour” with the youth and claims he hired him as a travel assistant because he was unable to carry bags due to a medical condition.

But Lucien, who says he only advertises his services on Rentboy.com, told CNN he had been hired to carry bags and provide daily “sexual massages” of an hour at a time.

He showed the broadcaster a contract which required him to spend at least eight hours a day with Professor Rekers, including sharing two meals.

Lucien said Professor Rekers told him he had had boyfriends before the trip but has refused to say he is gay.

“I actually asked him over the phone, ‘Do you think you’re gay?’ and he said, ‘no’,” Lucien said.

A statement posted on NARTH’s website on Tuesday by Professor Rekers said: “I am immediately resigning my membership in NARTH to allow myself the time necessary to fight the false media reports that have been made against me.

“With the assistance of a defamation attorney, I will fight these false reports because I have not engaged in any homosexual behavior whatsoever.

“I am not gay and never have been.”

The association accepted the resignation, saying on its website that it “would hope that the legal process will sufficiently clarify the questions that have arisen in this unfortunate situation.”

However, NARTH has removed all other references to the professor from its website.

Professor Rekers has a long history of anti-gay advocacy.

He has written books about homosexuality and testified in 2008 against lifting Florida’s gay adoption ban.

He also co-founded the Family Research Council, which is the US’s most powerful Christian lobbying group. In a statement, it denounced his alleged behaviour but denied any association with him in the last ten years.