US president Donald Trump was the only leader at the Group of 20 Summit in Argentina who refused to sign a statement supporting moves to fight climate change.

As the Buenos Aires meeting drew to a close, leaders of the forum which consists of 19 countries and the European Union agreed to fix the world trading system - but only 19 of them agreed to support the Paris accord on fighting climate change.

Applause rose up in the hall as the leaders, including Trump, signed off on a final statement at the end of a two-day summit.

The statement acknowledged flaws in the world trading system and called for reforming the World Trade Organisation.

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The statement also said 19 of the members reiterated their commitment to the Paris climate accord but the US reiterated its decision to withdraw.

The non-binding agreement was reached after all-night talks by diplomats.

A copy was obtained by The Associated Press.

Trump remains a skeptic of climate change.

In an interview with The Washington Post, the president said he doubted the scientific consensus that the planet is getting warmer because of man-made pollutants that are being released into the air.

"One of the problems that a lot of people like myself, we have very high levels of intelligence but we're not necessarily such believers," Trump said.

"You look at our air and our water and it's right now at a record clean."

When asked whether climate change is caused by humans, Trump said: "As to whether or not it's man-made and whether or not the effects that you're talking about are there, I don't see it - not nearly like it is."

Last week, the federal government released a wide-ranging report which found that climate change will cost the U.S. economy hundreds of billions of dollars by the end of the century, damaging everything from human health to infrastructure and agricultural production.