Oxfam has launched a fresh campaign to pressure the world's governments to boost investment in agriculture and better manage food supply to create a fairer and more sustainable food system it says is currently "broken."

Unless  governments help support a new and more efficient way to grow and distribute the planet's food supply, it won't be enough to meet burgeoning food demand, which is expected to rise 70 percent by 2050, the non-for-profit body said.

The G20 must invest in the 500 million small scale farms in developing nations which offer the greatest potential for increasing global yields -- and they must help them adapt to a changing climate, Oxfam said. The campaign, called Grow, was presented in conjunction with the  "Growing a Better Future" report.

Oxfam said governments must also regulate commodity markets and reform flawed biofuels policies to keep food prices in check. It said the policies include flawed laws to promote biofuels which are depleting the world of sufficient grain and other food commodities, and must be changed. The ethanol industry, for example, could contribute to a doubling of corn prices in the next  20 years, it said. This would hit the world's poor the most at a time when 8 million people in Africa are already struggling with hunger, Oxfam said.

Former President Lula of Brazil, who is helping support and promote Grow, said in a statement: "We can't wait anymore. Political leaders and global companies must act now to ensure that all people can put food on their table."

"There are no excuses," he said. "We have the capacity to feed everyone on the planet now and in the future. If the political will is there, no one will be denied their fundamental human right to be free from hunger."

As part of Grow, Oxfam hopes to "expose governments whose failed policies are propping up the broken food system and the clique of 300 – 500 powerful companies who benefit from and lobby hard to maintain it."