U.S. President Barack Obama has announced a new global partnership to involve the private sector in improving food security in Africa, as wealthy nations struggle with shrinking budgets.

President Obama announced the effort in Washington Friday, as leaders of the Group of Eight leading industrialized nations prepared to hold their annual economic summit at the Camp David presidential retreat outside the U.S. capital.

Mr. Obama said that 45 companies, from major international corporations to African companies and cooperatives, have pledged more than $3 billion toward the new effort to help boost agriculture. But Mr. Obama insisted that the private sector commitments are not intended to replace aid, saying the United States will continue to make “historic investments” in development. He said the U.S. has a “moral obligation” to lead the fight against hunger and malnutrition.

“Some have asked in a time of austerity whether this alliance is just a way for government to shift the burden onto somebody else. I want to be clear. The answer is no.”

Mr. Obama said the pledges from the private companies, along with contributions from donor countries, are aimed at boosting farmers' incomes and helping 50 million people lift themselves out of poverty over the next 10 years.

The U.S. president addressed African leaders from Ethiopia, Ghana and Tanzania during the speech in Washington, which he said will be the first three countries to undertake the effort. African Union chair and president of Benin, Thomas Boni Yayi, was also present for the speech and will take part along with his fellow African leaders in what Mr. Obama described as a “special” G-8 session Saturday devoted to the food security challenge.

Following the speech, President Obama welcomed new French President Francois Hollande to the White House for their first one-on-one meeting. Mr. Hollande, who was sworn in this week, has called for a change in Europe's current focus on austerity to address the eurozone sovereign debt crisis.

Speaking to reporters following the meeting, President Obama said much of his discussion with President Hollande centered on the situation in the eurozone. Mr. Obama said they both agreed that it is an issue of “extraordinary importance” not only to the people of Europe but also to the world economy.

The austerity pact has led to a political standoff in cash-strapped Greece, where voters rejected political parties that agreed to harsh budget cuts in exchange for financial assistance.

Mr. Obama and Mr. Hollande will be joined at Camp David by German Chancellor Angela Merkel, the prime mover behind the Eurozone austerity treaty, plus the leaders of Canada, Britain, Italy, Japan and Russia. Russian Prime Minister Dmitri Medvedev is attending in place of President Vladimir Putin.

U.S. National Security Advisor Tom Donilon told reporters Thursday the leaders of the Group of Eight nations are expected to discuss global oil markets, energy and climate, the transition in the Middle East and North Africa and the eurozone debt crisis during the two-day summit.

Mr. Hollande will also play a central role in the two-day NATO summit that will begin Sunday in Mr. Obama's hometown of Chicago. The new French president has pledged to remove all his country's troops from Afghanistan by the end of this year — two years before all NATO troops are scheduled to leave.

Donilon says the meeting of the alliance is an opportunity to discuss the transition of Afghan forces taking the security lead from international forces. He notes the talks will build on progress made and plans the president talked about in a recent visit to Afghanistan.

“Chicago is a critical milestone in the next step towards a responsible ending of this war, towards our achieving, very importantly, our goals in this effort in Afghanistan and really kind of the execution of the strategy that the president laid out in his speech at Bagram.”

He says President Obama will meet with Afghan President Hamid Karzai on the sidelines of the talks Sunday. He says there are no plans at the moment to hold a private meeting with Pakistani President Asif Ali Zardari.

Islamabad closed supply routes to NATO nearly six months ago to protest U.S. airstrikes that mistakenly killed 24 Pakistani troops near the Afghan border.

Pakistani officials demanded an unconditional apology for the deadly NATO air strikes. But Washington only offered condolences and Islamabad retaliated by cutting off NATO ground supply routes. The U.S. withdrew as much as $3 billion of promised military aid, as relations with Pakistan deteriorated.