US President Barack Obama has announced a $3bn (£1.9bn) plan to boost food security and farm productivity in Africa, US officials say.

They say the initiative is aimed at alleviating shortages as world food supplies are being stretched by rising demand in Asia's emerging markets.

Food security is also on the agenda of this weekend's G-8 meeting.

The summit near Washington is being dominated by Europe's debt crisis and a possible Greek exit from the eurozone.

Mr Obama unveiled the Africa plan ahead of his first meeting with new French President Francois Hollande.

He said investments in African agriculture by private US companies, for a total of more than $3bn, would address 'unacceptable' starvation.

'It's a moral imperative, it's an economic imperative and it's a security imperative,' Mr Obama said.

''There is no reason why Africa cannot feed itself.'

The president also said that while the summit would address Europe's fiscal situation, it was 'also important, also critical, to focus on the urgent challenge that confronts some one billion men, women and children around the world: the injustice of chronic hunger.'

The leaders of Ghana, Benin, Ethiopia and Tanzania have been invited to attend the G-8 meeting on food security.

The head of the US Agency for International Development (USAID), Rajiv Shah, said earlier the move showed the administration's commitment to boosting world food production as rising wealth in Asia drives consumption.

'By taking this new approach, we believe that it's possible to move 50 million people out of the condition of poverty and hunger,' he told reporters.

'You cannot have stability and security as long as regions and countries and communities are deeply food-insecure.'

The UK and other G-8 nations as well as African countries, aid agencies and multinational companies will also take part in what will be known as the New Alliance for Food and Nutrition Security. - BBC