Assem al-Gohari, who also heads the Illicit Gains Authority, said most of the funds - which are now frozen - were held by Mr Mubarak's elder son Alaa.
The balance is reportedly held by his younger son, Gamal Mubarak.
Both sons are standing trial on corruption charges and complicity in the killing of protesters.
Their father is also charged with killing the protesters, who were campaigning in January and February this year to depose him after three decades in power.
Some of the anger that led to Mr Mubarak's overthrow was fuelled by the belief that he and his sons had illegally amassed vast amounts of wealth corruptly.

Money laundering 
 
Alaa Mubarak, 49, is a businessman who largely kept out of politics.
Gamal Mubarak, 47, was a leading politician in the former ruling National Democratic Party and was widely seen as his father's heir apparent.
Mr Gohari said the Swiss authorities were investigating whether Alaa Mubarak was involved in money laundering.
Switzerland has already frozen the assets of the Mubarak family and other former Egyptian government figures.
Mr Gohari estimated these were worth about $450m - most of these funds are believed to belong to the two sons.
Switzerland promised last week to speed up the return of funds once held by members of the Mubarak government and those of the ousted Tunisian President Zine al-Abidine Ben Ali.
"Switzerland is the seventh financial centre in the world. It is the first in terms of restitution of funds stolen by dictators," said Swiss foreign ministry spokesman, Valentin Zellweger.