Winston Peters calls Labour turmoil a 'disgraceful orgy of speculation'

Deputy Prime Minister Winston Peters has returned to the Beehive and described a sexual assault allegation saga engulfing the Labour Party as a "disgraceful orgy of speculation and innuendo".

Peters on Monday attended Cabinet for the first time in four weeks after what Prime Minister Jacinda Ardern last month called time off after a leg operation for an old rugby injury.

In his absence, Labour has been dealing with the fallout of the mishandling of serious accusations about a former staffer.

Asked what he had made watching the issue from the sidelines, the NZ First leader told Newstalk ZB's Heather du Plessis-Allan that there had been a lack of presumption of innocence.

"All that went flying out the window in what a disgraceful orgy of speculation and innuendo. None of which I can tell you, even from where I sit and what I know, will be proven by the evidence," he said.

"What I saw unfolding is actually a disgrace."

Peters said he would await the results of the QC investigation into the complaints and that "some people have been treated very unfairly".

He also accused the National Party of hypocrisy over its criticism of Labour.

"I would have started back on [deputy opposition leader] Paula Bennett and her party and read their pedigree out on these matters and what had done in the past," he said.

"And I would have said: 'When all this was happening, how did the opposition parties like the Greens, NZ First and Labour act? Well we didn't act in that tawdry way you have'."

The comments appeared to reference National's handling of its own allegations last year.

Meanwhile, Peters was also coy about his leave - which has piqued interest among media - but rejected reports he had a knee operation.

"It was a private [operation] and when you pay for the bill you can start asking the questions," he said.

"Sadly, you all thought the worst, but you were wrong ... I'm back."