Cairo (CNN) -- Two sons of ousted Egyptian president Hosni Mubarak stood trial Monday in a Cairo criminal court on charges of insider stock trading, with prosecutors alleging they acquired millions illegally by using insider information about a bank sale.
Gamal and Alaa Mubarak allegedly gained the money through the 2007 sale of the Al Watany Bank of Egypt. They stood trial with seven others, including the deputy chief executives of the bank.
Prosecutors told the court the defendants conspired to acquire illegal funds and 80% of the bank's shares.
Gamal Mubarak illegally made nearly 500 million Egyptian pounds, or about $82 million, from the bank sale, prosecutors said. His brother, Alaa, used insider information about the bank to gain 12 million Egyptian pounds, or about $1.9 million, authorities allege.
The two "purposely withheld vital information on the sale of the bank from other share traders to implement their crime and violated the principles of transparency and equality between traders," according to a statement from prosecutors.
They are further accused of selling their shares to strategic partners at EFG Hermes. Yasser El-Malawny and Hassan Heikal, EFG Hermes joint chief executive officers, are among the other defendants in the case.
Following Monday's proceedings, the trial was adjourned until September 8. The court denied a request by the Mubaraks' attorneys that they be released on bail. The attorneys had pointed out that the other seven defendants were freed on bail, but not allowed to travel. The travel ban remains in place, the court ruled.
All nine of the defendants, including the Mubaraks, deny the charges.
Gamal Mubarak told the judge there was "no basis whatsoever to these accusations."
"Unfortunately, these are all lies," Alaa Mubarak said. "None of this happened."
Gamal and Alaa Mubarak have been imprisoned since spring 2011. They were acquitted of corruption charges in another case last month.
EFG Hermes is one of the Middle East's most prominent investment companies, with branches in nine Arab countries. Hermes released a statement last May saying its two executives acted properly in the acquisition of the Al Watany bank. The National Bank of Kuwait took a nearly 100% stake in the bank in November 2007.
"The two chief executive officers had no personal interest, gain or any dealings or trading in the shares of the Al Watany Bank of Egypt," Hermes said, adding that the company has taken the necessary legal actions to defend them.
The bank's deputy chief executives are also accused of gaining "concealed" percentages and conducting dealings without informing the stock market authority publicly, which is against the laws of the Egyptian Central Bank and the stock market.
Gamal and Alaa Mubarak offered last month to pay a 2 billion-pound ($330 million) fine in reconciliation, but prosecutors denied the request, according to Adel Al-Saeed, a spokesman for the general prosecutor.
The prosecutor "insisted they plead guilty first, and all the defendants must also join them in this reconciliation effort," he told CNN. "Only one other defendant offered to pay."
Hosni Mubarak, who led Egypt for more than 30 years, was ousted by the Arab Spring protests last year and was found guilty of charges relating to the killings of hundreds of anti-government demonstrators during the revolution. The 84-year-old is reportedly in declining health and was moved to a military hospital last month.