Zimbabwean President Robert Mugabe turned 90 yesterday, far from home on a medical trip that has intensified concerns about his health and stoked a simmering succession battle in a country under his thumb for more than three decades.

When Mugabe left for Singapore this week, spokesman George Charamba maintained the official denial of reports that Africa’s oldest President was suffering from prostate cancer, saying the trip was for a “routine and long-planned” cataract operation.

Charamba assured Zimbabweans that Mugabe would be back home for his official birthday celebrations tomorrow, but the timing of the trip – just days before the milestone – has fired up speculation that Mugabe’s health is failing.

In an interview with state TV, his traditional mouthpiece, Mugabe claimed to be “as fit as a fiddle” but his slow speech and puffy appearance only made tongues wag harder.

I do not want to leave my party in tatters

“I know he’s a very old man and we should not expect him to look like a 25-year boxing champion or rugby player, but it’s exactly for that reason that he should be retiring,” said one 50-year-old currency trader after seeing the interview.

As with many Zimbabweans discussing a leader accused of staying in power by force, he did not want his name to appear in print.

A June 2008 US diplomatic cable published by Wikileaks said Mugabe had prostate cancer that had spread to other organs, and had been urged by his physician to step down from office.

But Mugabe went on to win another five years in power at an election last year that he says will allow him to quell factional fighting in his Zanu-PF party over who will one day fill his shoes.

“When the day comes and I retire, yes, sure, the day will come. But I do not want to leave my party in tatters. I want to leave it intact,” he said in the state TV interview.

Joice Mujuru, Mugabe’s deputy in both the government and the Zanu-PF party, is leading the race to replace him, analysts say, closely followed by Justice Minister Emmerson Mnangagwa – a powerful former defence minister nicknamed ‘The Crocodile’.

If Mugabe dies without resolving the succession issue, there are fears Zanu-PF could implode in a factional fight with the potential to suck in the military.

The Constitution says if the President dies mid-term, the ruling party will elect a successor. Zanu-PF’s charter says this must be done at a party congress where, technically, any aspiring leader can contest.

Mujuru has consolidated her support base with newly elected provincial executives but she needs Mugabe’s open endorsement to overcome reservations in the top ranks of the army about her capacity to lead, analysts ­­­say.