Mr Mugabe, who will be 87 in February had medical examinations while on holiday in Malaysia earlier this month. He returned home to Harare but his prostate suddenly flared and he has returned to Kuala Lumpur for the operation.
Diplomatic sources in both Harare and South Africa said this was a "serious" operation and Mr Mugabe was ill, but within his Zanu PF party there is confidence he will return home within a week and recover fully.
Mr Mugabe, now in a troubled inclusive government with the Movement for Democratic Change has had remarkable health so far.
Last month at the annual Zanu PF conference he said he would lead his party in fresh elections later this year.
Morgan Tsvangirai, now MDC prime minister in the coalition government says elections should only be held when substantial political and legislative reforms and a new constitution are in place.
Mr Tsvangirai easily beat Mr Mugabe in the first round of the last presidential elections in 2008, but pulled out of the run off after Zanu PF killed more than 160 of his supporters. -Telegraph