Leaders of the Group of 20 major economies, known as the G20, have pledged to inject $US5 trillion ($8.2 trillion) in fiscal spending into the global economy to ease the economic impact of coronavirus.

Key points: The G20 leaders expressed concern for fragile countries and populations like refugees

The G20 leaders expressed concern for fragile countries and populations like refugees Coronavirus fears forced G20 world leaders to meet via internet

Coronavirus fears forced G20 world leaders to meet via internet WHO urged G20 nations to ramp up production of protective gear for health workers

Showing more unity than at any time since the 2008-2009 financial crisis that led to the G20's creation, the leaders said they committed during a videoconference summit to implement and fund all necessary health measures needed to stop the virus's spread.

In a joint statement, the group pledged to ensure the flow of vital medical supplies and other goods across borders and to resolve supply chain disruptions.

As many countries enact export bans on medical supplies, the G20 leaders said they would coordinate responses to avoid unnecessary interference, doing "whatever it takes to overcome the pandemic".

Leaders of the world's most powerful economies were forced to convene virtually on Thursday. ( AP: Pang Xinglei )

"Emergency measures aimed at protecting health will be targeted, proportionate, transparent, and temporary," they said.

The G20 leaders also expressed concern about the risks to fragile countries, notably in Africa, and populations like refugees, acknowledging the need to bolster global financial safety nets and national health systems.

"We are strongly committed to presenting a united front against this common threat," the G20 leaders said in the joint statement that was released after their 90-minute call.

Leaders pledge to work together

Saudi King Salman chaired the video call from his office in Riyadh, Saudi Arabia. ( AP: Saudi Press Agency )

The G20 was meant to be held in Saudi Arabia, but the coronavirus crisis forced world leaders to join the chair, King Salman Bin Abdulaziz al Saud, in a meeting over the internet.

German Chancellor Angela Merkel took part from her apartment where she is in home quarantine.

The G20 led the response to the global financial crisis just over a decade ago and its members promised to work together again to fight the virus outbreak.

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Some countries, such as the UK, promised more money for research into a vaccine, while the G20 as a whole broadly pledged more support for international agencies such as the World Health Organisation.

The International Monetary Fund has asked the G20 to double the amount available for emergency financing.

"Otherwise it will take years to overcome the effects of widespread bankruptcies and layoffs," IMF managing director Kristalina Georgieva said.

Ms Georgieva told the summit 80 countries have already asked for help.

United Nations secretary-general Antonio Guterres — who had already called for a global ceasefire — also said sanctions should be waived.

He asked G20 nations to fund a collective coronavirus stimulus package to cushion the world economy.

G20 nations said they had collectively committed $US4.8 trillion ($7.9 trillion) to keeping economies afloat during the outbreak.

"We commit to do whatever it takes and use all available policy tools to minimise the economic and social damage from the pandemic," the final summit statement said.

Putin calls for halt to trade wars and sanctions

Russia's President Vladimir Putin called for countries to lift sanctions and stop trade wars. ( AP: Alexei Druzhinin )

Russia's President Vladimir Putin called for countries to lift sanctions and stop trade wars to ensure essential supplies can reach all nations while the COVID-19 pandemic rages.

Mr Putin urged world leaders to "create so-called 'green channels' which would be free of any trade wars or sanctions for mutual supplies of medical goods, food, equipment, and technology".

"Ideally, we should introduce a moratorium, a solid moratorium on restrictions on essential goods as well as financial transactions for buying them," he said.

The head of the World Health Organisation, Tedros Adhanom Ghebreyesus, urged G20 nations to ramp up production of protective gear for health workers.

"We call on all of your nations to increase production, remove export bans and ensure equity of distribution," he said.

China's President Xi Jinping agreed, with the pandemic giving weight to China's criticism of the United States' "trade war".

"I want to call on all G20 members to take collective actions — cutting tariffs, removing barriers, and facilitating the unfettered flow of trade," he said.

"Together, we can send a strong signal and restore confidence for global economic recovery."