Labour leader Phil Goff is standing by South Australian Premier Mike Rann and does not believe allegations made against him.
Mr Rann has been defending himself after an ex-barmaid's made claims in paid interviews of having a sexual affair with him.
Mr Rann, born in Britain but educated in New Zealand, says he had a "flirty" friendship with former Parliament House barmaid and waitress Michelle Chantelois but denied ever having sex with the mother of two.
Mr Goff has known Mr Rann, who spoke at a Labour Party conference this year, for years,
"I've known him for a long time. He's a person of integrity. There's no reason for him to deny this if it were true. He was a single man at the time, it was before his engagement. He says that it's not true I'd accept his word for that," Mr Goff said.
"I think before anybody in the media runs a story with that sort of allegation and innuendo they need to check out whether their facts are right. I don't believe they are."
Ms Chantelois, in a paid interview with the Seven Network screened on Sunday, claimed she had a lengthy affair with the premier which included sex on his desk in Parliament House and at a city golf course.
She repeated her allegations to New Idea magazine in a story published on Monday.
"Last night's Channel Seven programme was, in my view, outrageous," Mr Rann said.
"It was based on malice, it was deliberately designed to do me damage both personally and politically.
"There was a whole series of things that were said on the programme that were totally and absolutely false."
He said claims of sex in public places were ridiculous.
He intends to take legal action against the Seven Network and New Idea.
Mr Rann is Australia's longest serving premier, who faces an election on March 20.
Mr Rann moved to South Australia from New Zealand in the late 1970s.
