Mubarak`s wealth comes from offshore accounts deposited in secret bank accounts or invested in luxury homes and hotels, according to `The Guardian`.
The British claimed that in over 30 years of presidency, the former Egyptian president had access to investment deals that over time have generated huge profits.
Most of these gains, according to the newspaper, were taken offshore.
Mubarak owned properties in Manhattan and Beverly Hills, while much of the money was kept in banks in England and Switzerland, reported earlier by the Al Khabar newspaper.
Christopher Davidson, a professor of political science at Durham University, said that Mubarak has managed to gather wealth through a series of business partnerships with various foreign investors and companies with whom he was closely connected since the military stage.
The 70 billion dollars would put Mubarak comfortably ahead of Mexican business magnate Carlos Slim, who is worth about 53.5 billion dollars, and Microsoft founder Bill Gates, with 53 billion dollars.