Image copyright Reuters Image caption Mrs Okonjo-Iweala, currently Nigeria's finance minister, is also a former World Bank managing director

A group of former World Bank officials has written a letter backing Nigeria's Finance Minister, Ngozi Okonjo-Iweala, to be its next president.

Traditionally the post is given to the candidate put forward by the US, which this time is Dr Jim Yong Kim.

But in an open letter, 35 former economists and managers said the Bank should choose the next chief on merit.

Another group of economists this week signed a petition backing Colombia's Jose Antonio Ocampo.

This is the first time the World Bank has had to choose between candidates since its creation more than 60 years ago.

The executive board of the Bank has to choose between Mrs Okonjo-Iweala, a former World Bank managing director, Jose Antonio Ocampo, a former finance minister of Colombia, and Jim Yong Kim, a public health expert and president of Dartmouth College in the US.

The Bank is holding interviews next week and plans to select the successor to outgoing president Robert Zoellick by 20 April, when it starts its spring meetings with the IMF.

Tradition

The three-way fight is attracting increasingly passionate comment from candidates' supporters. It has also shone a light on the way the World Bank chooses its head.

[Mrs Okonjo-Iweala] would be the outstanding World Bank president the times call for Open letter from economists

The US, which is the Bank's largest shareholder, has always picked the Bank's president. It, Europe and Japan have 54% of the votes.

Under an informal arrangement, in return, Europe appoints a European as head of the International Monetary Fund (IMF), which is the Bank's sister institution. It is currently run by Frenchwoman Christine Lagarde.

Emerging economies have become increasingly unhappy with this system and are pushing for change.

The leaders of Russia, Brazil, China, India and South Africa recently called for a review of that weighted voting system.

The nations, sometimes referred to as the Brics countries, are working to chose a joint candidate, according to the Brazilian finance minister Guido Mantega.

Speaking after a meeting with the US-nominated Jim Yong Kim, he said Brazil has not yet made up its mind who to promote.

"By late next week Brazil should have a position on the matter and I will talk with the other Brics."

He said Dr Kim had vast experience with the developing world, but he would wait until he had met the other candidates before making up his mind.

Transparency

The letter in support of Mrs Okonjo-Iweala, which is signed by high-ranking managers and economists, including Tunisia's central bank chief, Mustapha Nabli, criticised some aspects of the selection process.

[Jose Antonio Ocampo's] intellectual leadership and commitment to development led to significant improvements in these [UN] institutions Petition in support of Mr Ocampo

It said that it still involves nomination by governments, based in part on nationality, and without an agreed list of qualifying criteria.

It called for the process to be made in "an open, transparent, merit-based, and competitive manner rather than simply appointed in line with understandings that no longer reflect the world as it is today".

Mrs Okonjo-Iweala herself has called for a televised debate between the three candidates.

Her supporters said: "We believe that Mrs Okonjo-Iweala has outstanding qualifications across the full range of relevant criteria."

Mrs Okonjo-Iweala "would bring the combination of her experience as finance and foreign minister of a large and complex African country with her wide experience of working at all levels of the Bank's hierarchy in different parts of the world, from agricultural economist to managing director".

The World Bank contenders Kim Yong Jim: Currently president of Dartmouth College. Backed by the US for the job. Born in Seoul, the 52-year-old is a leading figure in global health. A doctor and former director of the HIV/Aids department at the World Health Organization.. Medical doctorate and PhD in anthropology. Ngozi Okonjo-Iweala: The Nigerian finance minister, 57, has been endorsed by three African countries - South Africa, Angola and Nigeria. Previously a managing director at the World Bank. PhD in regional economics and development. Jose Antonio Ocampo: Currently professor of professional practice in the International and Public Affairs department of Columbia University. Nominated by Brazil - but not endorsed by - in the name of the Dominican Republic. Former Colombian finance minister and has held other posts in government, including agriculture. He has held a number of positions in the United Nations, including as UN Under-Secretary General for Economic and Social Affairs. BA in economics and sociology and a PhD in economics from Yale University. World Bank president candidates

It says "she would be the outstanding World Bank president the times call for" and pointed out that should would be the institution's first female leader.

They said they cared too much about the institution not to speak out.

Future shape

The petition is support of Mr Ocampo was signed by economists from countries including China, India and Brazil, as well as two former governors of the Chilean central bank.

It pointed to his background working for UN agencies where "his intellectual leadership and commitment to development led to significant improvements in these institutions contribution to development thinking and to development policy design".

He has also been setting out his views of the future shape of the World Bank.

Writing in the Financial Times newspaper, he said the Bank's core mandate must remain that of reducing poverty, addressing growing inequalities that have appeared in recent decades and eliminating gender inequalities.

Mrs Okonjo-Iweala has also been outlining what she thinks should be the Bank's main goal.

She said that it should be creating jobs, in both developing and developed countries, with a particular focus on youth unemployment because of the knock-on social problems it caused.

Dr Kim, who once did a turn as a rap artist at a social event at Dartmouth College, has the support of Canada, Japan and South Korea, where he was born, as well as the US.

He has not yet given an interview about his views on the role at the World Bank, but has described it in a statement as "one of the most critical institutions fighting poverty and providing assistance to developing countries in the world today".