Farid al-Dib, in an interview published in US magazine "Foreign Affairs," said he had "submitted the sources of the funds obtained from the sons' work in global stock-market consultation with clients outside of Egypt who have nothing to do with Egypt's market".
"The revenues entered a joint account owned by the two brothers, which was then separated on March 1st, 2008. The funds in the accounts, after years of (accumulating) interest, reached over $300 million.
"Is it wrong for a man to make legal profits?"
Last month, Egyptian Deputy Justice Minister Assem al-Gohari said the lion's share -- $300 million -- was held by Mubarak's elder son Alaa, a businessman who kept out of politics.
Gohari, who heads the Illicit Gains Authority, said the balance was held by his younger son Gamal, a leading former ruling party politician who had widely been seen as his father's heir apparent.
Both sons are in custody in a Cairo prison as they stand trial on an array of charges, including corruption. The next hearing is set for December 28th.
The assets of Mubarak's two sons make up the great majority of the $460 million in Egyptian funds frozen by the Swiss government since the veteran strongman's overthrow in February, Gohari said.
Dib also spoke of the financial situation of the ailing former president and his wife, Suzanne.
Mubarak's "health bill is paid by the government, as the law permits with any president or former president. His wife lives off his monthly pension, which reaches up to 93,000 Egyptian pounds (about $15,500).
"Mubarak and his wife do not own a single dollar inside or outside of Egypt."
Mubarak, who was forced to quit in February following massive street protests, has been on trial since August 3rd on charges of involvement in the killings of protesters and corruption.