Obama's $3 billion boost for Africa

On Saturday, Obama and the other G-8 leaders will be joined at Camp David by the heads of four African countries - Ghana, Ethiopia, Tanzania and Benin - for a session on food security

President Barack Obama will announce private sector pledges worth $3 billion (£1.9 billion) aimed at alleviating hunger in Africa

The US president will also urge the world's biggest economies to make good on their own financial promises.

Mr Obama is due to unveil the food security initiative in a speech today in Washington that begins four days of international summitry. World leaders are gathering at Camp David, the presidential retreat in the Maryland mountains, later in the day for a summit of the Group of Eight leading industrial nations. Obama heads to Chicago on Saturday evening for NATO meetings.

Leaders at the G-8 economic summit have sought to focus some of their efforts in recent years on the plight of the developing world. At the 2009 summit in L'Aquila, Italy, Obama championed a food security initiative that resulted in $22 billion in pledges from G-8 leaders and other nations.

The private sector commitments Obama was announcing Friday build on that effort, administration officials said. The goal is to achieve sustained agriculture growth and raise 50 million people out of poverty over the next 10 years. 

"It's not about replacing aid," said Mike Froman, a top Obama adviser for international economics. "It's about combining aid with private capital." 

Obama is also expected to call on countries to fulfill the financial food security pledges they made in 2009. The pledge period for L'Aquila Food Security Initiative ends later this year, and some humanitarian groups say much of the promised money has not been dispersed. 

The G-8 will release an accountability report this weekend detailing how much of the $22 billion is still on the sidelines. Administration officials say the U.S. is on track to fulfill its $3.5 billion pledge. 

On Saturday, Obama and the other G-8 leaders will be joined at Camp David by the heads of four African countries - Ghana, Ethiopia, Tanzania and Benin - for a session on food security. 

While administration officials say Obama will urge wealthy nations to maintain their commitment to alleviating hunger in Africa, the U.S. and other G-8 countries were not expected to announce any new financial pledges of their own.