Africa's political leaders are being offered a $5-million prize and a stipend for life if they do not plunder the national coffers or rig elections. Former South African president Nelson Mandela, British Prime Minister Tony Blair and former United States president Bill Clinton are backing the initiative to be formally launched on Thursday in London by a foundation started by a Sudanese-born telecom tycoon, Mo Ibrahim.

Mandela said the award, which is for former leaders who have shown "excellence in leadership", will contribute to "Africa's political and economic renaissance". Blair said it supported efforts to "encourage exemplary leadership".

But sceptics say that the award will only emphasise the power wielded by individual leaders and fails to recognise the real causes of corruption and abuse of power.

Ibrahim said the prize is necessary to encourage African leaders to consider a fourth alternative to those they currently face when nearing the end of their term, namely "relative poverty, term extension, or corruption".

"Nothing is as important as good governance in ensuring development and reducing poverty," Ibrahim told the Guardian. "Africa's leaders face many challenges and this award will help recognise those of them that have done well."

The annual winner will be chosen by a board that includes Mary Robinson, the former Irish president. He or she will receive the $5-million over 10 years and $200 000 a year thereafter. They are also allotted $200 000 a year to be given to good causes.

But Hassan Lorgat, head of the South African branch of the global anti-corruption group Transparency International, said the thinking behind the prize is flawed because it puts the emphasis and responsibility for good governance on one person.

"It targets individuals and at best you can pick a few dozen leaders for the prize and that reaffirms the principle of the 'big man'," he said.

"It doesn't read Africa's problems correctly. Those who keep governments accountable are ordinary people and that accountability needs to be strengthened. That's where he should have put his money. Or into the Parliaments that could hold leaders accountable."

Ibrahim (59) who worked for British Telecom before launching an African mobile phone company, Celtel, and amassing a personal fortune estimated at more than $650m, will fund the prize through his charitable foundation.

Some African leaders, such as Zimbabwe's Robert Mugabe and Uganda's Yoweri Museveni, appear to be motivated to cling to power for power's sake not money, or out of a belief that they are irreplaceable.

Other leaders, such as the late Mobutu Sese Seko of Zaire and a succession of Nigerian military rulers, used the huge amounts they plundered to spread largesse and buy loyalty.

Lorgat said many of the worst leaders remained in power with the backing of powerful foreign governments.

"These guys were useful tools. Everyone knew Mobutu was stealing but they turned a blind eye. Africa got the leaders other people wanted," he said.

The first award will be made next year. - Guardian Unlimited Â