An evangelical Christian MP has admitted to having an affair with his assistant and apologised for his "completely inappropriate" behaviour.

Steve Double, 49 and MP for St Austell and Newquay, told the Cornish Guardian he had an affair with his 26-year-old married assistant, Sarah Bunt. "It wasn't a one-off but it was only a few weeks," he said.

The confession comes after the MP and former church pastor released a statement on Monday saying he deeply regretted the pain he had caused, but didn't confirm rumours of the affair.

Double, who is married and a father of three, was elected in 2015 on a pledge to protect "the traditional fabric of family life" and described families as the "foundation of the community".

Double's wife, Anne, who works in his office as a senior caseworker and diary manager, yesterday vowed to stay with her husband.

"I'm not throwing away 30 years of marriage for the sake of a few hours," she said in a separate statement.

Double's public apology followed rumours he had a "tryst" with Bunt, who worked alongside Double's wife in his constituency office. Asked if Bunt was still working there, Anne Double told the Daily Mail: "She's on leave. Put it that way."

In his previous statement Double said he was "committed to making our marriage a success".

He said: "I have behaved completely inappropriately and deeply regret the pain I have caused those closest to me."

"Anne and I are committed to being together and seeking to move forward in our marriage.

"I accept I have work to do to recover the trust and respect of those around me.

"I would respectfully request that people give us the time and space we need at this time."

Double has become known for his outspoken Christian views in Parliament. He won the Cornwall seat from the Liberal Democrat Stephen Gilbert and in his campaign said he hoped to "provide community leadership and support the structures that bind us together".

On his website last year he wrote: "Like many people, family has a very special place in my life. I believe that strong families are the basis of a strong society.

"In my view many of the problems and challenges our country faces could be improved by supporting families and this is something I am committed to do."