Organizers of a $5 million prize for former African leaders that aims to shine a spotlight on democracy and outstanding leadership has again failed to find a winner after no one met the criteria.

To win the prize, set up by Sudanese telecoms tycoon Mo Ibrahim in 2006, a leader must have been a democratically elected head of state or government and left office in the past three years, serving only their constitutionally mandated term. He or she must have shown outstanding leadership in developing their countries and lifting people out of poverty.

The seven-member prize committee did not select a winner for the 2015 award, the Mo Ibrahim Foundation said in a statement on Thursday.

Since being launched in 2006, the Ibrahim Prize has only been awarded four times: to Mozambique's Joaquim Alberto Chissano, Botswana's Festus Gontebanye Mogae, Cape Verde's Pedro De Verona Rodrigues Pires and Namibia's Hifikepunye Pohamba. South Africa's Nelson Mandela was awarded an honorary prize in 2007.

"When we launched the prize 10 years ago, we deliberately set a very high bar," said Ibrahim, chairman of the foundation. "We want the prize to shine a spotlight on outstanding leadership to provide role models right across society, as well as supporting laureates to continue to serve the continent by sharing their wisdom and experience."

Although elections have become more common on a continent once better known for military coups and instability, some leaders have remained in office long beyond their mandates, often pushing through constitutional changes to hold on to power.

The winner receives $5 million over 10 years and then $200,000 a year for life, and can apply for another $200,000 a year for good causes they support.