UPDATE 1-Obama to unveil $14 bln in U.S. corporate investments in Africa

(New throughout, adds investment pledges from business leaders, World Bank)

WASHINGTON, Aug 5 (Reuters) - U.S. companies pledged new investment in Africa on Tuesday as part of $14 billion in construction, clean energy, banking, and information technology projects to be unveiled by U.S. President Barack Obama at an event showcasing U.S. economic interest in the fast-growing region.

Business leaders told the U.S.-Africa Business Forum they wanted to seize opportunities in the region, home to six of the world's 10 fastest growing economies, although some said they may have been late to the party.

"We gave it to the Europeans first and to the Chinese later but today it's wide open for us," said General Electric chief executive Jeff Immelt, who on Monday announced a $2 billion investment in infrastructure and worker skills.

The forum, part of a three-day Africa summit in Washington, will allow dozens of African heads of state to mingle with U.S. and African executives and spotlight projects to improve infrastructure, finance, supply chains and energy security.

Dangote Group President Aliko Dangote, announcing plans to invest $5 billion in energy projects in sub-Saharan Africa jointly with Blackstone Group funds, said nothing worked if there was no power.

The group counts cement making, flour milling and sugar refining among its activities . Dangote called for U.S. export credit agency, the Export Import Bank, to remain open, praising its support for African companies buying U.S. goods.

The World Bank forecasts Africa's economic growth will accelerate to more than 5 percent in 2015 and 2016 but estimates one in three Africans, or 600 million people, need electricity.

World Bank President Jim Kim announced $5 billion in financing and investment guarantees for Power Africa, a privately funded program to install 10,000 megawatts of new generation capacity and connect 20 million new customers across Africa by 2018.

Walmart CEO Doug McMillon said the retailer had faith that regional governments would work to ensure a secure business environment and rule of law.

Walmart's $2.6 billion investment in the region in 2011, when it bought a majority stake in local Massmart Holdings Ltd, was "just the beginning," he said.

Walmart believes "the whole region, not just South Africa, but sub-Saharan Africa, including Nigeria and Kenya and so many countries around the continent, are going to do the right things to create the right rules, create transparency, some of those infrastructure investments so that the whole thing works."

More than 90 U.S. companies are slated to participate including Chevron Corp <CVX.N, Citigroup Inc, Ford Motor Co, Lockheed Martin Corp, Marriott International Inc and Morgan Stanley. Many already have a foothold in Africa.

Obama will take part in a discussion with corporate chief executives and government leaders at the event, and will unveil the total pledged in new investment.

"These investments will deepen U.S. economic engagement in Africa, fueling growth that will support broader African prosperity and emerging markets for U.S. businesses, which will support jobs in both the United States and Africa," a White House official said on Monday, in a preview of Obama's remarks.

Former New York Mayor Michael Bloomberg and former President Bill Clinton also attended the event. U.S. Commerce Secretary Penny Pritzker welcomed financial commitments by U.S. firms.

"These deals and investments demonstrate that the time is ripe to work together as partners, in a spirit of mutual understanding and respect - to raise living standards in all of our nations and to address the challenges that impede our ability to develop closer economic bonds," she said.

"Make no mistake: our economic and commercial partnership is a two-way street. Goods and services exports from the United States to African markets support roughly 250,000 jobs here at home."

(Additional reporting by Lesley Wroughton; Editing by David Gregorio)