SYDNEY (AFP) - Australia's former attorney-general has launched a scathing attack on Labor colleague and ex-prime minister Kevin Rudd, calling him a rude and disorganised "bastard" who should quit parliament.

Mr Rudd, who lost national elections to Tony Abbott last month after ousting Julia Gillard as premier in June, has a reputation as a hot-tempered politician and Nicola Roxon did not mince her words in a speech on Wednesday evening.

"Although I was frustrated beyond belief by his disorganisation and lack of strategy, I was never personally a victim of his vicious tongue or temper," said Ms Roxon, who was health minister under Mr Rudd from 2007-2010 before being elevated to attorney-general under Ms Gillard's rule.

"I did, however, see how terribly he treated some brilliant staff and public servants.

"Good people were burnt through like wildfire - losing senior people like chiefs of staff and deputies or contemptuously ignoring their advice left the government weaker."

Labor has been dogged by in-fighting for years, with two prime ministers toppled. New leader Bill Shorten vowed to draw a line under the past rancour after his election last weekend.

But Ms Roxon, who has quit politics, was determined to put her thoughts on record, saying the party did the right thing by getting rid of Mr Rudd in June 2010 in a shock coup by Ms Gillard, an ally and friend of hers.

"Removing Kevin was an act of political bastardry for sure. But this act of political bastardry was made possible only because Kevin had been such a bastard himself to so many people already," she said.

His sudden downfall mystified the Australian public and Ms Roxon admitted the party should have better explained why they demoted him to foreign minister.

"We didn't explain the dysfunctional decision-making and lack of strategy... we didn't talk about his rudeness or contempt for staff or disrespect for public servants."

Mr Rudd stepped down as Labor leader after his crushing defeat by Mr Abbott in September but stoked speculation of a comeback down the track with ambiguous remarks in his concession speech, although he has since kept a low profile.

Ms Roxon said he should quit parliament altogether to give Mr Shorten the chance to rebuild the party.

"I believe we must also confront the bitter truth that as long as Kevin remains in parliament, irrespective of how he behaves, pollsters will run comparisons with him and any other leader," she said.

"In my opinion - and it is only my opinion - for the good of the federal parliamentary Labor party and the movement as a whole, Kevin Rudd should leave the parliament."