'Green revolution' for Africa

Speaking at King's College London, the Nobel Peace Prize winner described feeding the continent as the "most pressing challenge we face" and urged on the international community to do more in the fight against climate change.

In a wide-ranging lecture on Africa in the World Today, Mr Annan also stated that African leaders needed to do more over Zimbabwe, calling the situation in the country "intolerable and unsustainable."

Giving the university's annual Commemoration Oration, the Ghanaian diplomat said Africa had made progress in terms of healthcare, education, governance and investment.

But he said the continent was now at crucial point in its development.

Mr Annan said: "Africa is at a crossroads. It can continue to move forward or retreat in the face of old and new challenges."

"The most pressing challenge we face is food supply. We need action to tackle the immediate food crisis in Africa and the long-term impact that climate change will have on food supplies and agriculture across the continent."

"Without immediate action we are certain to see, indeed are seeing, many thousands of more deaths."

He added: "We need nothing less than a green revolution transforming every aspect of farming on the continent."

Farmers need better seeds, soils, access to water and fertilisers, support from governments and the international community, Mr Annan said.