JOHANNESBURG (Reuters) - Zimbabwe opposition leader Morgan Tsvangirai is  out of danger  in hospital in South Africa after being airlifted from Harare at the weekend following the sudden onset of severe vomiting, a party source said on Tuesday. Tsvangirai, who is due to challenge President Robert Mugabe in elections next year, was recovering well but had been told by doctors to avoid stress and strain until at least the weekend, the source said. The 65-year-old s symptoms came on suddenly at a meeting of his opposition coalition, the Movement for Democratic Change (MDC), on Thursday evening in Kadoma, a city around 160 km (100 miles) southwest of the Zimbabwe capital. The MDC sought to play down Tsvangirai s hospitalization, describing it as  routine  and denying local media reports that he was on life support after being airlifted to Johannesburg in the early hours of Saturday morning. Tsvangirai has been receiving treatment for colon cancer since last year but says he is in good health. His sudden illness was not thought to be related to his cancer or cancer treatment, two party sources told Reuters. It comes a month after Vice President Emmerson Mnangagwa, a favorite to succeed 93-year-old Mugabe, was rushed to South Africa for emergency medical care. Mnangagwa, who has since returned, denied local media reports he had been poisoned. 