Well-known economists from Colombia and Nigeria were nominated to contend with the US candidate, a Korea-born, US-raised physician known for fighting to bring medical services to impoverished communities around the world.

 

The three were American nominee Jim Yong Kim, currently president of Dartmouth College; Colombian Jose Antonio Ocampo, a professor at Columbia University; and Nigerian finance minister Ngozi Okonjo-Iweala.

 

The announcement launched an unprecedented competition to lead the 187-nation development lender, with the Bank's executive board to interview the three candidates in the coming weeks.

 

The Bank said it expected to select its new president "by consensus" by its 2012 Spring Meetings with the International Monetary Fund that begin on 20 April.

Zoellick plans to step down at the end of his term in June.

 

In a Rose Garden news conference at the White House on Friday, US President Barack Obama unveiled Kim as Washington's nominee, a physician who has worked for decades in global health issues.

 

Earlier Africa's leading economies South Africa, Angola and Nigeria announced their support for Okonjo-Iweala, who spent more than two decades at the Bank, rising to managing director, the number two position under Zoellick, before returning to Nigeria.

 

Ocampo, who originally nominated himself, is a former finance minister and central bank chief; it was not immediately available which country had endorsed him.

 

Thanks to a tacit agreement, the United States, the Bank's biggest stakeholder, has always chosen the head of the World Bank, and has always named an American, while Europe has always named one of its own to head the International Monetary Fund.

 

But that pact has triggered anger from developing and emerging economies seeking greater representation to reflect their rising contributions to the global economy.

 

The job is crucial, overseeing the Bank's mission to provide financial and technical assistance to countries struggling to rise out of poverty.

 

The Washington-based bank lent $57.3 billion last year and has more than 9,000 employees worldwide.

 

The surprise choice of Kim, a physician little-known beyond academic and global health circles, marked a break with Washington's usual candidates tapped from politics or Wall Street.

 

A Harvard-trained doctor and anthropologist, Kim, 52, is the former director of the department of HIV/AIDS at the World Health Organization. He became the president of the Ivy League college Dartmouth, in New Hampshire, in July 2009.

 

"It's time for a development professional to lead the world's largest development agency," Obama said in a Rose Garden news conference with Kim at his side.

 

"Jim has spent more than two decades working to improve conditions in developing countries around the world," the president said. "I believe that nobody is more qualified to carry out that mission than Doctor Jim Kim."

 

The US nomination of Kim makes him an instant favourite for the job.

 

According to a US Treasury official, Kim will be traveling abroad in the coming weeks seeking support for his bid. France, another big Bank stakeholder, appeared supportive.

 

"The principle is that there is this choice by the United States at the World Bank and the Europeans at the IMF. There is no reason at this point to change that," French Foreign Minister Alain Juppe told AFP after Kim was nominated.

 

But Okonjo-Iweala, widely respected for her work at the Bank in the past, could mount a stiff challenge.

 

"I consider the World Bank a very important institution for the world and particularly for developing countries deserving of the best leadership," she said Friday.

 

"So I look forward to a contest of very strong candidates, and am I confident? Absolutely."

 

Jeffrey Sachs, another popular development economist who nominated himself for the job and picked up a number of small country endorsements, withdrew Friday when Kim was nominated.

 

"Jim Kim is a superb nominee for WB," Sachs tweeted.

 

"I support him 100 per cent. I thank all who supported me and know they'll be very pleased with today's news."