HARARE: When UN chief Ban Ki-moon urged African leaders not to cling to power at a summit last month, Zimbabwean President Robert Mugabe responded by saying he would continue "until God says 'come'".

Mugabe turns 92 on Sunday and, judging by those comments, has no intention of stepping down - despite being Africa's oldest leader and the only president Zimbabwe has known since independence in 1980.

His life presidency aspirations could frustrate the feuding big-hitters of his ruling ZANU-PF party who have been trying for years to position themselves for a post-Mugabe political era.

They will also fuel criticism from opponents of the government, who say the internal conflict is distracting it from its job of dealing with a stagnating economy and responding to the worst drought in a generation - charges denied by ministers.

"Amid this looming starvation, coupled with an economy on the ropes, no one is paying attention to this national crisis. There is no government response as ZANU-PF is too pre-occupied with the succession issue of President Mugabe," main opposition leader Morgan Tsvangirai said on Tuesday.

Critics blame Mugabe for many of the problems facing the country. They say his policies, including the seizures and redistribution of white-owned commercial farms, drove one of Africa's most promising economies into nearly a decade of deep recession until 2008 that cut its output almost in half.

They also say Zimbabwe's sluggish economy and low productivity - the jobless rate is around 85 percent - has left it ill-equipped to deal with the drought, which has left 3 million people in need of food aid, about a quarter of the population.

For his part, Mugabe defends his land seizures as necessary to correct colonial injustices and says the economy has fallen victim to sanctions by Western countries that are punishing him for seizing white-owned land.