Mo Ibrahim was speaking at a two-day forum in Dar es Salaam
Many African states are too small to continue to exist independently, Sudan-born magnate Mo Ibrahim has told a conference in Tanzania.
Mr Ibrahim said the idea that 53 small African countries thought they could compete with China, India, Europe and the US was a "fallacy".
Trade within Africa accounts for just 4-5% of the continent's international trade, something that is "not viable".
The tycoon said Africa "needs scale" to compete with the big economic players.
"We need scale and we need that now - not tomorrow, the next year or the year after."
The BBC's Peter Greste in Nairobi says Mr Ibrahim was referring to economic integration rather than political unification.
Sudan-born mobile phone entrepreneur
Moved to UK in 1974 to study
By 1983, director of BT Cellnet
Founded Mobile Systems International, which he sold to Marconi in 2000
Then set up Celtel, used by 25m Africans
2007: Started African leadership prize
2008: Named UK's most influential black person
Speaking to an audience that included Tanzanian President Jakaya Kikwete, Mr Ibrahim said Africans were poor, hungry and going without.
"Something is drastically wrong. I think we have the right to ask our leaders: are they really serious?" he said.
Mr Ibrahim surprised African leaders last month when the $5m (£2.9m) Ibrahim prize for good governance was withheld.
The prize is given to a democratically elected leader from sub-Saharan Africa who has served their term and left office.
South Africa's Thabo Mbeki and Ghana's John Kufuor had been among the favourites.