Key Points:

Deputy Prime Minister Michael Cullen is not about to apologise for calling National leader John Key a "scumbag" and a "rich prick" in Parliament yesterday.

A spokesman for Dr Cullen said this afternoon that he had not spoken with the Deputy Prime Minister about an apology.

He said Dr Cullen has not been asked to apologise and the subject has not been raised.

Dr Cullen made his interjection during a heated debate after Mr Key referred to Otaki MP Darren Hughes as being "the son Helen Clark never had".

He first called him a "rich prick" then repeatedly called him a scumbag. "You scumbag, John," he said. "Scumbag, scumbag."

It appeared Dr Cullen took offence at the statement that Helen Clark had not had children. He said it was the second day in a row Mr Key had "dragged members on this side's personal lives or relatives or characteristics into the debate".

He had done so on Tuesday when he referred to Dr Cullen's wife, Anne Collins - Mr Key said she had supported list MP Russell Fairbrother for Labour's Napier candidacy in 2002 when Dr Cullen signed the nomination form of Mr Fairbrother's unsuccessful challenger this time, Stuart Nash.

"I think he needs reminding that there are limits on those matters or that will come back on members opposite and many of them are exposed in that respect."

Mr Key said he had used the reference to Mr Hughes because he thought that was how he had described himself in the Independent newspaper.

Mr Hughes said he had not described himself in that way, and it had been written by a journalist.

Dr Cullen once called former National deputy leader Don McKinnon a "born to rule prick".

Mr Key said last night he had had five years of verbal abuse from Dr Cullen - though not the words used yesterday.

"The last time it got really ugly was when he called me a working-class scab."

Mr Key said calling him a "rich prick" was Dr Cullen showing his true feelings. Dr Cullen fundamentally had an aversion to people who had been successful.

"And what does that speak of for a Government it claims wants people to be successful," he said.