With the opposition trying to impeach him and his popularity at an all-time low, President Robert Mugabe has lashed out at Zimbabwe's white minority, threatening genocide trials for all who fought against him in the independence war. Mugabe told supporters on Wednesday that Ian Smith, the white leader he helped overthrow two decades ago, and all whites who fought against black guerrillas would face trials for war crimes. Speaking as he arrived for a debate in Oxford on Thursday, Ian Smith responded to these latest threats, saying Mugabe's actions belonged to a man clinging onto the last vestiges of power. He challenged Mugabe to set up a truth and reconciliation committee, saying that he had nothing to fear. Arriving at Oxford Union Thursday night, the former white leader of the former British colony of Rhodesia, Ian Smith laughed off President Mugabe's latest threat to put him on the stand. Mugabe is calling for all whites who fought against black guerrillas to face trials for war crimes. Mugabe has said the nation's 70,000 whites - less than 1 percent of the population of 13 million - mostly opposed his government and had spurned offers of forgiveness and reconciliation. Smith rejected Mugabe threat, saying that the blame for the violence lay squarely on Mugabe's shoulders.