Who am I to question Mugabe's health – PM

Johannesburg - Zimbabwe's prime ministerMorgan Tsvangirai was reticent on Thursday about President Robert Mugabe's claim that he was fit enough to still be president at 88.

"Is President Mugabe fit enough to lead?" said Tsvangirai in response to a question at a news conference in Johannesburg.

"Well, he says so himself [that] he's fit enough to lead, so who am I to question his state of health," said Tsvangirai, who entered a government of national unity with Mugabe in 2009.

"Of course he is of an advanced age, but he has stated publicly that he is fit, so we will go by his assessment of his own health," Tsvangirai said on the sidelines of a conference to encourage investment in Zimbabwe.

At a birthday rally on Wednesday Mugabe, who has been in power since 1980, reportedly described himself as "fit as a fiddle".

Tsvangirai told the media that the inclusive government had been a frustrating experience that nobody could brush aside, but it had lasted.

"There were some sceptics who thought this was not going to last for six months, and we are three years. The government of national unity is holding. The government of national unity is discharging its mandate."

The former trade union and opposition leader, and organiser of stayaways and marches to oppose Mugabe's rule, denied he had "gone soft", believing instead there was a "phase for everything".

"How can I as prime minister throw stones when I have to negotiate with Mugabe? We are in a new phase and I hoped that people would understand me from that perspective."

Zimbabwe is in the process of writing a new constitution ahead of an election.