Zimbabwe opposition leader Morgan Tsvangirai suffered severe vomiting after a party meeting and was airlifted from Harare to a Johannesburg hospital, a senior party source says.
Mr Tsvangirai's condition was currently stable, the source said, adding that the sudden illness did not relate to Mr Tsvangirai's ongoing cancer treatment.
The 65-year-old's symptoms came on suddenly while at a meeting on Saturday of his main opposition Movement for Democratic Change (MDC) on Thursday evening in Kadoma, a city around 160km southwest of the capital Harare, the source said.
He was taken to hospital on Friday, the source added.
Mr Tsvangirai, who leads a broad coalition of opposition parties, is due to challenge his long-time political foe President Robert Mugabe at an election next year.
Mr Tsvangirai said last year that he was being treated for colon cancer.
Two other Zimbabwean political sources confirmed the details of his illness and move to South Africa.