Actor Arnold Schwarzenegger says seeing a marriage counsellor with estranged wife Maria Shriver was "the biggest mistake" he has ever made.

The 67-year-old actor, who separated from Shriver in 2011 after 25 years of marriage after he confessed that he had fathered a son with their housekeeper Mildred Baena in 2007, said their decision to seek therapy was a waste of time, reported E! Online.

"I think that people should get help when they need help."

We are not against that. But in my particular case, it was not helpful," Schwarzenegger said.

The "Terminator" star, who has four children, Katherine, 25, Christina, 23, Patrick, 21, and Christopher, 17, said the therapy was "nonsense."

"It was the biggest mistake I’ve ever made… It was absolutely, totally counterproductive to our future relationship or to any hope to get together or anything like that. It was just nonsense talk. It was the biggest mistake.

Maria talked me into it."