Africa needs investment of 65 billion dollars over the next 20 years if food production is to keep pace with the rapid expansion of its population, a UN agency said on Monday.

The fundraising target is set out in the "Blue Revolution" programme to be examined by delegates at a conference in Sirte on water for agriculture and energy in Africa.

"With its population set to double by 2050, Africa needs to triple its food production in the next four decades," the UN's Food and Agriculture Organisation said.

"It also needs to bring electricity to millions of factories and homes to spur development. Blue Revolution is designed to harness Africa's largely untapped water resources to produce more food and energy," the agency said.

The programme aims to ensure water supplies in villages, for irrigated land and in big rivers, Jacques Diouf, FAO director general, said at the opening of the ministeral conference, organised under FAO auspices.

"It is the first time that a balance sheet for short, mid and long terms has been drawn up so exhaustively and so precisely," he told delegates representing 53 African countries, 40 of which have sent their water or farm ministers.

They are expected to approve 964 projects prepared by the programme for submission to funding organisations.

Diouf stressed the urgency of a "massive acceleration" in investment in agriculture, which represents 17 percent of gross domestic product and 57 percent of jobs in Africa.

The disappointing performance of African farm production, which has failed to keep up with population growth in recent decades, has had "tragic" consequences for the continent, he said, noting that of the 36 countries hit by the global food crisis, 21 are African.

In the past 30 years, cereal production per person in Africa has risen only 0.14 percent, including 0.07 percent in sub-Saharan Africa, leading to a 136 percent increase in imports to 56.4 million tonnes in 2008, the director general said.

Irrigated land forms an average 20 percent of arable land around the world, including 38 percent in Asia, but only 7 percent in Africa. Only four percent of water reserves are exploited in Africa compared with 20 percent in Asia, Diouf said.

Last year, the food crisis had a severe impact on Africa, "increasing by 24 million the number of people in sub-Saharan African suffering from chronic hunger," he said.

On energy, Diouf said there is a "serious shortfall" in supplies despite Africa's "considerable hydroelectric and solar potential."

Sub-Saharan Africa is the only region in the world where the number of people without access to electricity is growing, he said.

In that region, 74 percent of people were living without access to electricity in 2002. The proportion with power fell to 5 percent in some countries and 2 per cent in some rural areas.

"Blue Revolution was established in close cooperation with each African country. Once the projects have been discussed, we will start a dialogue with the governments concerned as well as providers of funds," Diouf told journalists.

The conference, which runs until Wednesday, is organized by FAO together with the Libyan government, the African Union, the African Ministers' Council on Water (AMCOW), the African Development Bank and the Economic Commission for Africa, among others.