Half of the world's countries have approached the International Monetary Fund for emergency loans to weather the financial crisis sparked by the global coronavirus pandemic.

More than 100 countries so far have asked for emergency assistance, Kristalina Georgieva, IMF's managing director, told a meeting of G20 finance ministers and central bank governors on Wednesday.

She said the IMF is ready to use its "full toolbox and $1 trillion firepower" of lending capacity, noting that 10 countries have so far received emergency funding, and half of the remaining countries should receive their requested financial lifelines by the end of April.

Georgieva's comments come after the fund issued a stark warning that the global economy is on track for the deepest downturn since the 1930s and governments and health officials must work together to prevent an even worse outcome.

The IMF head said "everything is on the table in terms of measures we can take," and encouraged central banks to "spend as much as you can."

"But keep the receipts," she added. "We don't want accountability and transparency to take a back seat in this crisis."

In an interview with CNBC, the IMF chief acknowledged that the fund has a reputation for imposing tough conditions on countries seeking bailouts.

But this time, "we are asking for one thing only: Please pay your doctors and nurses, make sure that your health systems are functioning, and that your vulnerable people and first [responders] are protected," Georgieva told the network.

The IMF said on Tuesday that it expects global GDP will contract by 3% in 2020, a far worse recession than the one that followed the global financial crisis of 2008, and a 180-degree reversal of its previous forecast in January when it was expecting growth of 3.3% this year.

The fund said there is a risk of the recession extending into 2021 if policymakers fail to coordinate a global response to the virus.