People facing starvation could almost double if international aid is not given to poorer countries tackling COVID-19, says the former New Zealand prime minister, Helen Clark.

She is among more than 200 former world leaders, economists and health experts who are calling on the G20 to meet and pledge $2.5 trillion dollars to help developing countries.

A joint letter has been penned by the group, who believe the money needs to be spent to support the fight against the coronavirus and stimulate the global economy.

"We are looking at the moment, if there isn't a co-ordinated global response, at adding another 130 million people to the 135 million already on the brink of starvation, according to World Food Program," Clark tells CGTN Europe.

She says $2.5 trillion is the amount the International Monetary Fund says is needed for emerging markets to come through the coronavirus crisis.

"We have seen the economic damage that has been done to the highly developed economies like the United States, like the United Kingdom and others, we are not hearing so much about the world's poorest countries," she said.

"Even middle-income countries, like the tourism-dependent ones, in the small and developing states where the economies just came to a standstill."

Compared with the Global Financial Crisis more than a decade ago, Clark says it is a "tragedy" that there isn't the same leadership. She thinks for that reason the G20, a forum for nations and the EU to discuss economic matters, needs to come to the fore.

"Now we face a global leadership vacuum, the G20 currently is chaired by Saudi Arabia, which has not taken the initiative to rally countries in the way that was done in 2009," she continues.

"We should be asking the G20 because it represents 85 percent of the world's GDP."

Check out The Pandemic Playbook, CGTN Europe's major investigation into the lessons learned from COVID-19