Welcoming the $1.1 trillion package committed by the world leaders at the G-20 Summit in London, UN Secretary General Ban Ki-Moon has said the developing and poor countries must get the "crucial" funds to avert a human development crisis.

The G-20 nations also "reaffirmed previous commitments to increase aid and help countries achieve the Millennium Development Goals," Ban said in a statement, referring to the ambitious anti-poverty targets with a 2015 deadline.

This means that these nations are promising at least $300 billion in aid over the next two years, he said. "For the poorest countries this will be crucial. The world will be watching," he said in a statement.

According to new World Bank data, developing countries' economic growth will slow sharply to 2.1 per cent this year, marking a 3 per cent drop from 2008. As a result, some 53 million more people would fall into poverty this year, living on less than $1.25 a day, due to the crisis.

Additionally, the world economy will contract by 1.7 per cent compared to last year's 1.9 per cent growth, marking the first global decline since the Second World War.

The G-20 leaders committed considerable new resources for the International Monetary Fund and the World Bank and asked the UN to monitor the impacts of the current and future crises on the world's most vulnerable, Ban added.