A new level of brutality for debate?

ANALYSIS: Parliamentary debate can be robust and at times brutal, but the scenes that unfolded in the House this afternoon took that to a new level.

Tensions had been running high even before MPs settled into question time.

More on the trouble at the centre on Christmas Island

Labour MP Kelvin Davis was waiting in the foyer, where reporters take the opportunity to interview MPs and ministers on their way into the debating chamber, and approached Prime Minister John Key.

He told Mr Key he was being "gutless" and needed to do more to help the New Zealand detainees being held on Australia's Christmas Island.

Although unusual, there was nothing threatening in the approach but, despite that, a member of Mr Key's Diplomatic Protection Service (DPS) pushed Mr Davis aside.

If there was a security threat, fair enough - but the Prime Minister was in no physical danger.

It is not the first time DPS have stepped in to protect MPs from uncomfortable questions, most notably when they blocked reporters from asking then-National Party leader Don Brash about the Exclusive Brethren during the 2005 election.

But what happened in Parliament soon after did little to present Parliament and MPs in a favourable light.

United Future leader Peter Dunne summed it up when he described this afternoon's question time as "one of the more despicable question times in terms of the standards of conduct, and pettiness and stupidness, all around, frankly".

At the centre of it all is the issue of New Zealanders being detained on Christmas Island.

Mr Davis has become personally involved, having travelled to Christmas Island to meet the detainees and become their mouthpiece in the New Zealand media.

Still, it is highly questionable whether that warrants accusations that he and his Labour colleagues are backing sex offenders and rapists over the rest of New Zealand, as asserted several times by Mr Key in Parliament.

As for Mr Key, he is speaking directly to a constituency that has no sympathy for the detainees, and who take the view that if they have committed criminal acts, they have to pay the consequences.

While there are serious offenders among the Christmas Island detainees, there are also people who have committed minor crimes, including shoplifting.

This morning, Mr Key was assuring reporters he and government ministers were advocating on behalf of the detainees to make sure their cases are being expedited to limit the time they have to spend on Christmas Island.

That all went out the window during Parliament's Question Time, as Mr Key drove home the point that there were real security concerns that would prevent the immediate return of some of the detainees.

MPs regularly indulge in insults across the Chamber, sometimes in good humour but more often with a sharp edge.

But many MPs believe Mr Key went too far when he twisted Mr Davis' advocacy for New Zealand detainees into accusations he and his fellow Labour MPs were supporting sex offenders and rapists.