Foreign Affairs Minister Murray McCully has called on the big boys of the United Nations to give up some of their veto rights.

In his speech to the UN General Assembly in New York overnight, Mr McCully challenged the five permanent members of the security council (P5) to trim the grounds on which they could veto a council resolution.

When the UN was established in 1945, the P5 had asked for the power of veto over security council resolutions to protect their vital national interests, he said.

"Yet today, we routinely see the exercise of the veto in circumstances which have little to do with national interests," Mr McCully said.

"My request to the five permanent members is simply that they stick with what they said in 1945."

Citing paralysis over a UN response to civil war in Syria, Mr McCully said the security council was "at risk of losing its credibility".

"From all of this, the case for reform of the Security Council has become utterly compelling. Indeed, increasingly, the future credibility of the United Nations may depend upon it."

The P5 should agree to voluntarily confine its use of the veto to issues that clearly and directly affected their vital national interests and not to use their veto in situations involving mass atrocities.

New Zealand is bidding for a stint on the security council in 2015/16. Lobbying for the bid continued in New York at the weekend, and Mr McCully told the general assembly New Zealand was an "energetic candidate".

But time was also spent in support of Australia's tilt at a temporary seat in 2013/14, which goes to the vote next month.

Mr McCully told the Q+A programme he did not think New Zealand's chances for a seat would be affected by whether or not Australia's bid was successful.

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