Josh Duggar: '19 Kids and Counting' star 'assaulted two of his sisters'

Parents Jim Bob and Michelle Duggar have spoken to Fox News

Prominent Christian Duggar says he is 'sorry' for his actions (Associated Press)

Josh Duggar's parents Michelle and Jim Bob Duggar have told Fox News of how their son molested his sisters as they slept.

The heads of the family that star in programme 19 Kids and Counting said they felt like "failures" as a result of their son's actions.

They said that two of the five girls he is alleged to have molested as a young teenager were his sisters.

In the interview with Megyn Kelly, Jim Bob described the family's horror at their eldest son's admission.

"Twelve years ago, we went through one of the most darkest times that our family's ever gone through," he said.

"And our son Josh came to us on his own, and he was crying, and he had just turned 14, and he said that he had actually improperly touched some of our daughters."

The Duggar family photographed together in 2013 (Associated Press)

"We were shocked, we were just devastated," Michelle said. "We had one ray of hope, in that Josh had a tender conscience, and he was the one that came and shared it on his own."

Jim Bob spoke of the sense of failure the couple experienced following his confession.

"As parents, I think you feel like a failure when one of your kids does something wrong," he said.

The Duggars say they put up safeguards in their home to protect their girls from any future abuse.

Speaking of his son's actions, Jim Bob said: "He said he was just curious about girls, and he had basically gone in and just touched them over their clothes while they were asleep, and they didn't even know that he'd done it."

At the time, the couple had five daughters.

"Josh has done some very bad things," his mother Michelle said. "And he's very sorry."

Another interview, this time with his sisters Jessa and Jill will air on Friday.

Jessa acknowledged that what her brother did was "very wrong" but also added that she thinks some people have gone "overboard" in criticising him.

"I do want to speak up in his defense against people who are calling him a child molester or a pedophile or a rapist, some people are saying," she said.

"I’m like, that is so overboard and a lie really, I mean people get mad at me for saying that but I can say this because I was one of the victims."

Josh Duggar released a statement in May saying that he "acted inexcusably". He apologised to his family and stepped down as executive director of FRC Action - a lobbying arm of the Family Research Council.

Duggar's family preach against the use of contraception. Josh is the eldest child of the 19-strong brood. Their parents Jim Bob and Michelle said they would "allow God to determine the number of children" they'd have.