Blair's support for the invasion of Iraq prompted Tutu to refuse last week to join a leadership conference in Sandton, to which Blair had been invited as a keynote speaker.

Writing in the British newspaper The Observer, Tutu called on Blair and former US president George W Bush to face trial in The Hague for their role in the Iraq war. He accused the two of lying about weapons of mass destruction and said the invasion left the world more unstable and divided "than any other conflict in history".

"The immorality of the decision by the US and Britain to invade Iraq in 2003, premised on the lie that Iraq possessed weapons of mass destruction, has destabilised and polarised the world to a greater extent than has any other conflict in history."

Tutu, awarded a Nobel Peace Prize in 1984, said Blair and Bush should face justice at the International Criminal Court, in The Hague.

He questioned the different standards for bringing African and Asian leaders to justice at The Hague compared with Western leaders.

Bush and Blair, he said, had "fabricated the grounds to behave like playground bullies and drive us further apart. They have driven us to the edge of a precipice where we now stand - with the spectre of Syria and Iran before us."

In his response, Blair said Tutu was simply repeating an old "canard" about the reasons for invading Iraq when "every single analysis of the evidence" showed the country had weapons of mass destruction.

He added: "To say Saddam's massacre of hundreds of thousands of his citizens is irrelevant to the morality of removing him is bizarre".

But Tutu said the cost of removing former Iraqi leader Saddam Hussein had come at the expense of more than 11000 Iraqi lives since the start of the conflict, with millions more displaced.

He said the invasion of Iraq had created the backdrop for civil war in Syria, and a potential conflict in the Middle East over Iran's nuclear ambitions.

Tutu said: "By the end of last year, nearly 4500 American soldiers had been killed and more than 32000 wounded. On these grounds alone, in a consistent world, those responsible for this suffering and loss of life should be treading the same path as some of their African and Asian peers who have been made to answer for their actions in The Hague," said Tutu.

Last week Tutu refused share a stage with Blair at the Discovery Invest Leadership Summit.