Isabel dos Santos, the eldest daughter of Angola's president, has become Africa's first female billionaire, US financial magazine Forbes has said.The 40 year old's shares in several Portuguese firms, including a TV cable company, and an Angolan bank put her on the billionaires' list, Forbes said.Her first venture was a restaurant in Luanda called Miami Beach, said the magazine that tracks the world's rich.Most of the population in oil-rich Angola live on about $2 (£1.25) a day.Angola is striving to tackle the physical, social and political legacy of a 27-year civil war that ravaged the country after independence from Portugal.The conflict ended in 2002 and Angola has since emerged as one of Africa's leading oil producers and fastest-growing economies.The family of President Jose Eduardo Dos Santos - who has been in power for 33 years - controls a large chunk of that economy."When you tease out the ownership and controlling interests in Angola it reads like a Who's Who of family members and party and military chiefs," Peter Lewis, an African studies professor at Johns Hopkins University in the US, told Forbes.Correspondents say Ms dos Santos is a relatively shy public figure despite her successful business career.Since setting up her restaurant in the capital, Luanda, in 1997 she has become an influential businesswoman in Angola and Portugal.With a 28.8% stake in Zon, she sits on the Portuguese media company's board and is its largest shareholder, Forbes said.