Archbishop Desmond Tutu has accused South Africa of losing the moral high ground by failing to stand up to Zimbabwe's president Robert Mugabe. The Nobel peace-prize winner told the BBC that using force should be an option to get rid of Mr Mugabe. Archbishop Tutu also said he was saddened that his own country appeared not to be on the side of Zimbabweans. Foreign Secretary David Miliband has meanwhile written to the Times, calling Mr Mugabe a "stain" on Zimbabwe. Archbishop Tutu said: "How much more suffering is going to make us say 'No we have given Mr Mugabe enough time?'" He also said South Africa had a leadership role as its president chairs the Southern African Development Community. But he told BBC Radio 4's Today programme that South Africa had instead betrayed its legacy by blocking firmer action from the United Nations. He added: "I want to say first of all that I have been very deeply disappointed, saddened by the position that South Africa has taken at the United Nations Security Council in being an obstacle to the security council dealing with that matter. "And I have to say that I am deeply, deeply distressed that we should be found not on the side of the ones who are suffering. "I certainly am ashamed of what they've done in the United Nations. "For the world to say no, we are waiting for South Africa's membership of the Security Council to lapse and then we can take action." The archbishop said that was an "awful indictment" to a country that had a "proud record of a struggle against a vicious system". He said: "We should have been the ones who for a very long time occupied the moral high ground. I'm afraid we have betrayed our legacy." Mr Miliband reaffirmed the UK's view that Mr Mugabe had to go in his letter to the Times. Source: BBC