US President Donald Trump has used what is likely to be his final appearance at an international summit to slam the Paris climate accord.

Mr Trump, who has fewer than two months left in office, told world leaders at the G20 summit that the Paris Agreement was designed to cripple the American economy, not to save the planet.

He went so far as to claim the US has reduced carbon emissions more than any country since formally exiting the Paris pact on November 4.

President-elect Joe Biden, who takes office on January 20, plans to reenter the global agreement that the US helped forge five years ago with the intention of reducing greenhouse gas emissions.

In what has been seen as another example of his refusal to concede election defeat, Mr Trump had earlier told the summit he wants to work with other world leaders “for a long time”.

In a subsequent video statement from the White House to the G20 meeting being hosted by Saudi Arabia, Mr Trump said the international accord was “not designed to save the environment – it was designed to kill the American economy”.

He said: “To protect American workers, I withdrew the United States from the unfair and one-sided Paris climate accord, a very unfair act for the United States.”

President Xi Jinping of China, the world’s largest emitter, defended the Paris accord during the discussions at the climate session.

He said the G20 should continue to take the lead in tackling climate change and push for the full implementation of the Paris accord.

“Not long ago, I announced China’s initiative to scale up its nationally determined contributions and strive to peak carbon dioxide emissions by 2030 and achieve carbon neutrality by 2060,” he said.

“China will honour its commitment and see the implementation through.”

More than 180 nations have ratified the accord, which aims to keep the increase in average temperatures worldwide “well below” 2C and ideally no more than 1.5C compared with pre-industrial levels.

Scientists say any rise beyond 2C could have a devastating impact on large parts of the world, raising sea levels, stoking tropical storms and worsening droughts and floods.

India’s prime minister, Narendra Modi, said “climate change must be fought not in silos but in an integrated, comprehensive and holistic way”.

COVID plan

Day two of the virtual G20 meeting hosted by Saudi Arabia. Photo: AAP

Instead of attending the summit’s “Pandemic Preparedness” event at the weekend, Mr Trump visited his golf course outside of Washington DC.

The remaining leaders of the world’s biggest economies vowed to spare no effort to supply COVID-19 drugs, tests and vaccines affordably and fairly to “all people”.

Prime Minister Scott Morrison was on the calls over the weekend, videoing in from The Lodge in Canberra where he is quarantining since returning from Japan.

In an effort to allay worries that the pandemic could deepen global divisions between rich and poor, the final communique said G20 nations will work to “protect lives, provide support with a special focus on the most vulnerable, and put our economies back on a path to restoring growth, and protecting and creating jobs for all.”

On vaccines, tests and treatments, the leaders said: “We will spare no effort to ensure their affordable and equitable access for all people.”

Mr Trump had earlier suggested the US might not be so quick to share a vaccine and instead was focused on making sure Americans would get vaccinated first.

Saudi Arabia’s King Salman said in his closing remarks that the group had “adopted important policies that will achieve recovery all the way to an economy that is resilient, sustainable, inclusive, and balanced”.

G20 leaders said that while global economic activity has partially picked up thanks the gradual reopening of some economies, the recovery is uneven, highly uncertain and subject to downside risks.

They reaffirmed their commitment to use “all available policy tools as long as required” to protect people’s lives, jobs, and incomes.

The G20 endorsed a plan to extend a freeze in debt service payments by the poorest countries to mid-2021 and a common approach for dealing with debt problems beyond that, according to the communique.

The Debt Service Suspension Initiative has helped 46 countries defer $US5.7 billion ($A7.8 billion) in 2020 debt service payments, short of the 73 countries that were eligible, and promised savings of around $US12 billion ($A16 billion).

-with AAP