Mr Haggard denies having sex with a gay prostitute

The Reverend Ted Haggard, ex-leader of the 30m-strong National Association of Evangelicals, said he bought methamphetamine but "never used it".

He denies having sex with the man but said he did receive a massage.

Mr Haggard has also stepped down temporarily from his 14,000-strong, Colorado-based New Life Church.

The issue is being played out against the backdrop of a vote in Colorado and seven other US states on Tuesday on whether to ban same-sex marriages.

Mr Haggard, 50, has been a vocal opponent of the unions.

'Pastor Ted'

Mr Haggard told journalists outside his home that he had bought methamphetamine.

"I bought it for myself but never used it. I was tempted but I never used it," Mr Haggard said. He said he threw it away.

It made me angry that here's someone preaching about gay marriage and going behind the scenes having gay sex

Mike Jones

Denver man Mike Jones, 49, this week told a radio show he had been paid to have sex with Mr Haggard nearly every month over the past three years.

Mr Haggard said he had not had sex with Mr Jones but did receive a massage after being referred to him by a Denver hotel.

The man who has temporarily replaced Mr Haggard as head of the New Life Church, Ross Parsley, said in an email message on Friday: "It is important for you to know that he confessed to the overseers that some of the accusations against him are true.

"He has willingly and humbly submitted to the authority of the board of overseers, and will remain on administrative leave during the course of the investigation."

Mr Jones said he had stepped forward because of the gay marriage issue.

"It made me angry that here's someone preaching about gay marriage and going behind the scenes having gay sex," he said.

Mr Jones said he was contacted by a man through the internet called Art.

Mr Jones said Art, who he later recognised as Mr Haggard, used methamphetamine to heighten their sexual encounters.

Influential ties

Mr Haggard, who is also known as "Pastor Ted" and has five children, has close contacts with the White House.

He became president of the National Association of Evangelicals in 2003.

The BBC's Jane Little in Washington says he is one of America's most influential and politically well-connected religious leaders.

His resignation comes as a blow for Republicans, who are hoping to energise a demoralised Christian base ahead of mid-term elections, our correspondent says.