A foundation promoting good governance in Africa says it will give anti-apartheid hero Archbishop Desmond Tutu of South Africa a $1m award for "speaking truth to power".

The London-based Mo Ibrahim Foundation announced the one-off award on Thursday, saying Tutu "is and has throughout his life been one of Africa's great voices for justice, freedom, democracy and responsible, responsive government".

A Nobel peace laureate, Tutu was an anti-apartheid leader during the most desperate years of the struggle against racist rule and has continued to be outspoken on world events.

He has been particularly critical of Israel's treatment of Palestinians and China's treatment of Tibetans.

Last month Tutu caused a stir, calling for Tony Blair, Britain's former prime minister, and former US president George W Bush to face trial in The Hague for their role in the Iraq war.

Writing in the Observer newspaper, Tutu, who turned down an invitation to attend a conference in South Africa where Blair was the main speaker, accused the two men of lying about weapons of mass destruction.

He said the invasion left the world more destabilised and divided "than any other conflict in history".

The foundation, founded by Sudanese-born Mo Ibrahim, also gives an annual $5m prize for good governance in Africa, awarded to a former head of state.

Recent recipients of the award include former presidents Festus Mogae, Joachim Chissano and Pedro Verona of Botswana, Mozambique and Cape Verde respectively.