Women are breaking glass ceilings worldwide and the next one to be shattered may well be at the United Nations, the world body's top-ranking woman says.

Helen Clark told AFP in an interview that she had yet to decide on whether to enter the race to be the next UN secretary-general and succeed Ban Ki-moon, who steps down in 10 months.

"Every country, every major organization like the UN should expect in the fullness of time to have a woman leader," Clark said.

"But it's still too rare a thing around the world. So for sure, the UN's day will come."

The former prime minister of New Zealand, who heads the UN's largest agency, the UN Development Programme (UNDP), also warned that climate change could wipe out gains in fighting poverty over the coming decades.

The challenge for UN development experts is to help countries "build resilience" so they can confront turbulent eco-systems and extreme weather, she said.

Clark will lead a ministerial-level meeting Wednesday to take stock of the UN's development agenda at a time when raging crises in Syria, Yemen and South Sudan are making a dent in global aid funding.

Development aid from the world's big donors totalled $135.2 billion in 2014, but some of those funds have since been diverted in Europe to refugee resettlement or fallen victim to austerity cuts.

UN humanitarian appeals have hit record levels in recent years as agencies struggle to address the world's worst refugee crisis since World War II and growing humanitarian needs.

"The countries that are not in severe conflict do worry about how much is left for development after all the major needs of the conflict crises are met," said Clark, 65, who served as prime minister from 1999 to 2008.

The meeting attended by some 80 ministers will seek to build on a summit in September during which the United Nations agreed on a new set of global goals to end poverty by 2030.

- Making a difference -

At the helm of UNDP for nearly seven years, Clark has been tipped as a possible candidate to succeed Ban and become the first woman in the top UN job, after eight men.

But Clark said she hadn't "offered an opinion" on whether to present her candidacy and sidestepped questions about her being naturally considered for the job as the UN's number three.

"I think there would be a difference," she said of a woman in the top job.

"How big it would be would very much depend on who the personality was and what the leadership style was, but I think people would notice a difference."

Clark went on to cite research that "points to women being better listeners, more consultative -- not less decisive, but more likely to take a broader range of opinions into consideration."

One of the high-profile women vying for the job is UNESCO chief Irina Bokova, who as a Bulgarian national would satisfy calls that the next secretary-general come from eastern Europe, the only region that has yet to be represented in the job.

Six candidates including three women have officially applied to become the next secretary-general but more will likely come forward ahead of hearings expected in April at the General Assembly.