http://news.bbc.co.uk/2/hi/africa/7779142.stmBishop of Pretoria Joe Seoka called on churches to pray for his removal, South African Press Association reports.His comments came as the US ambassador to Zimbabwe warned that the country was turning into a "failed state".On Thursday, Mr Mugabe said a deadly cholera outbreak had been stopped, as aid workers warned it was worsening.He said Western powers were plotting to use cholera as an excuse to invade and overthrow him.The World Health Organization says the outbreak has not been contained and the death toll has increased to 792 people, reports the AFP news agency.The UK minister for Africa Lord Mark Malloch-Brown said he did not know which world Mr Mugabe was living in.However, Mr Mugabe's spokesman George Charamba said the president's comments had been "sarcasm".The WHO has warned that the total number of cases could reach 60,000 unless the epidemic was stopped.US ambassador James McGee blamed the outbreak on Zimbabwe's political crisis and the failed economic policies of its government.He told reporters in Washington that hospitals in Harare remained closed, there was no rubbish collection and people were drinking from sewers.President Mugabe's ruling Zanu-PF party and the opposition Movement for Democratic Change (MDC) have been deadlocked in power-sharing negotiations for several months."The situation is truly grim. One man and his cronies - Robert Mugabe - are holding this country hostage," Mr McGee said, AP news agency reports.Bishop Seoka said that Mr Mugabe was a "person seemingly without conscience or remorse, and a murderer"."I believe it is now an opportune moment for all the church leaders to follow the retired Anglican Archbishop Desmond Tutu and the Archbishop of York, Dr John Sentamu, to call on God to cause the removal Mugabe from the office of the President of Zimbabwe," he said, calling for the prayers to be held next Tuesday."The church in South Africa has done this before with the apartheid regime and there is no doubt that God will hear our prayers even today."