(Bloomberg News) Africa may have as many as 200 "hidden" billionaires operating in the unofficial economy who will seek to legitimize their wealth in future, investor Mark Mobius said.

"There is a lot of hidden wealth," Mobius, who oversees more than $40 billion as executive chairman of Templeton Emerging Markets Group, said yesterday in London. "You hear about Dangote but there are maybe 200 with the same kind of resources that we do not see. The black economy is very big."

Aliko Dangote, Africa's richest man, is benefiting from the continent's economic growth, adding $3 billion to his wealth this year, taking him to $13 billion, according to the Bloomberg Billionaires Index. Africa's gross domestic product is forecast to expand an average 6 percent a year for the next five years if Europe, the largest trading partner, records 0 percent to 2 percent annual growth, Moody's Investors Service said today.

Dangote controls Dangote Group, one of the continent's largest conglomerates with publicly traded businesses in cement, sugar, flour and salt that make up about a third of the Nigerian Stock Exchange's market value. Many of the continent's richest individuals don't have publicly traded assets, Mobius said.

"What we see is that these very wealthy people will begin to want to legitimize their wealth by a listing, by putting these assets together, forming a company, listing it," Mobius told reporters yesterday. "Many of these people escaped to London or other countries in order to preserve their wealth. But it is going to get more and more difficult because of anti- bribery and all the rest that is going on in the U.S. and other parts of the world."

A lot of "hidden wealth" is concentrated in mining, Mobius said. Dangote said in May he "needs" to invest $7.5 billion in industries including mining in the next four years.

Mobius said he's considering buying shares in Kenyan banks, and is most interested in lenders that issue credit cards, open savings accounts and offer money-transfer services. The prospect of violence in Kenya ahead of elections next year was not a "big issue," he said.

A disputed 2007 vote sparked two months of ethnic and political violence that killed more than 1,000 people.

"The general consensus now is that they have sort of learnt the lesson," Mobius said. "I don't see it as being a big issue."