Australia and other G20 nations have struck a deal to co-ordinate efforts to tackle the coronavirus pandemic, as they collectively pledged $A7.5 trillion to kickstart the global economy.
Prime Minister Scott Morrison joined US President Donald Trump and other members of the G20 through a video link-up overnight.
The virtual summit was called by Saudi Arabia, which is chairing the forum this year.
In a communique issued after the meeting, Mr Morrison and other leaders described the pandemic as "a powerful reminder of our interconnectedness and vulnerabilities".
"This virus respects no borders," they said.
"Combating this pandemic calls for a transparent, robust, coordinated, large-scale and science-based global response in a spirit of solidarity."
In his contribution to the meeting, Mr Morrison is understood to have called for greater assurances that medical supplies and medicines will freely flow to those who need them.
China agreed to increase its supply of pharmaceutical ingredients and other supplies to the international market, in a move that will ease shortages in many countries.
The prime minister urged support for developing and vulnerable nations such as Pacific island countries, which had less capacity to deal with any outbreaks.
And any trade restrictions imposed as a result of the pandemic should be temporary and targeted, he argued.
Australia's contribution to date includes $189 billion in measures - almost 10 per cent of the country's GDP.
G20 finance, health and trade ministers are set to meet in coming weeks to develop specific action plans to deal with the economic and health impacts.
UN secretary-general Antonio Guterres told the leaders they needed a war-time plan.
"It took the world three months to reach 100,000 confirmed cases of infection," he said.
"The next 100,000 happened in just 12 days. The third took four days. The fourth, just one and a half.
"This is exponential growth and only the tip of the iceberg."
The meeting was not open to the media, but some leaders' statements were issued after it.
Russian President Vladimir Putin suggested setting up a special fund under the IMF that would offer interest-free loans, and he emphasised the need to create "green corridors" for free movement of supplies and technologies intended to deal with the epidemic.
He also proposed a moratorium on sanctions with regard to essential goods.
International Monetary Fund managing director Kristalina Georgieva asked G20 leaders for their backing to double the fund's $US50 billion ($A84 billion) emergency financing capacity.
She said vulnerable households and businesses need targeted financial support to stay afloat and get back to work quickly.
The final statement pledged "bold and large-scale fiscal support".
"We commit to do whatever it takes and to use all available policy tools to minimise the economic and social damage from the pandemic, restore global growth, maintain market stability and strengthen resilience."