International media have started weighing up Helen Clark's chances of becoming the next Secretary General of the United Nations, with the Guardian saying she was "a serious contender."

Ms Clark announced she was running for the role after months of speculation. 

MORE: Helen Clark will run for top job at UN

The Guardian's Ed Pilkington, based in New York, wrote the announcement "immediately places her as a serious contender" to be the next Secretary General - and the first woman to lead it.

"Her reputation as a fighter who survived nine years as premier amid the rough and tumble of New Zealand politics is being seen within senior levels of the UN as evidence she would be able to withstand the pressures of the famously thankless task of leading the world body."

He said her cost-cutting exercise at the UN Development Programme in 2014 could win her support from the United States which paid large sums into the UN coffers and had questioned the efficiency of it. 

Bloomberg said there was a push for a woman to take the role. However, it quoted John Langmore from the University of Melbourne saying Clark was "a stronger potential candidate than anyone from this region ever before" but it would be a tough race because of "strong sentiment" that Eastern Europe was next in line to have a Secretary General under the rotation of regions for the post. 

China's state news agency Xinhua reported Clark had a reputation for maintaining New Zealand's independent foreign policy stance, "notably resisting calls to join the U.S.-led invasion of Iraq in 2003."

Although the Eastern European issue could work against Clark, the candidate must be able to escape the veto of all five Permanent Members on the UN Security Council (the P5).

The UN Tribune said Clark was likely to be the favoured candidate for at least three of those five: France, the United Kingdom and the United States. It said the US had appreciated her decision to deploy troops to Afghanistan as former PM as well as her cost cutting at the UNDP.

However, the UN Tribune said she could run up against a brick wall when it came to getting Russia's support which was expected to favour an Eastern European candidate. 

It also put up a more dubious possible objection to Clark's candidacy, saying because the Queen of England was New Zealand's head of state some UN states could claim it breached an understanding that the Secretary General should not come from one of the P5 countries.

In Australia, much of the focus was on what Clark's announcement might mean for Kevin Rudd who has reportedly been lobbying for support but has not yet announced a candidacy. Reuters and the Huffington Post said it would be a blow to Rudd's chances.

Although more people may nominate, Clark will go up against at least seven others - including three women. They are Unesco Director-General Irina Bokova of Bulgaria; former Moldova foreign minister Natalia Gherman and Croatia’s former foreign minister, Vesna Pusic.

The other confirmed candidates are former Slovenia President Danilo Turk, former Prime Minister of Portugal Antonio Guterres, who was also a UN Commissioner for refugees and Montenegro Foreign Minister Igor Luksic.