UN Secretary-General Antonio Guterres called in a letter released Tuesday for G20 leaders, whose summit will be hosted by Saudi Arabia this weekend, to be bolder and more ambitious in their pandemic response.

Guterres urged for "the recognition" by the G20 group of largest economies  "that further debt relief will be needed.

"The G20 now needs to scale up ambition and deliver bolder measures to enable developing countries to address the crisis effectively and prevent the global recession from becoming a global depression," he said in the letter.

"As we tackle this unprecedented pandemic, the world needs unprecedented leadership that is united in its quest to respond to the crisis and recover better. The pandemic must be a wake-up call to all leaders that division is a danger to everyone, and that prevention saves money and lives," he continued.

The pandemic could put "an additional 115 million people" at risk of extreme poverty, Guterres said.

He also noted that "acute hunger could almost double," affecting more than 250 million people.

Guterres asked that debt suspension be extended until the end of 2021, and that the measure be expanded to include vulnerable middle-income countries.

He urged G20 leaders to "fill the financing gap of $28 billion" needed to increase access to tools and resources to fight Covid-19.

As vaccines grow closer to finalization  "we must also resist any form of vaccine nationalism," Guterres wrote.

He also called on the G20 to increase "investments in biodiversity, climate action and ecosystem restoration."