(CNN) -- Egypt's general prosecutor on Monday extended the detention of two of former President Hosni Mubarak's sons, saying further investigation is needed.
Gamal and Alaa Mubarak will be held for another 15 days, the prosecutor's office said in a statement, adding that members of the office went to Tora prison to conduct questioning. Gamal and Alaa Mubarak's lawyers were present, the statement said.
The two were being questioned "regarding the prices of their real estate, lands and their role in intervening in the program of settling Egypt's debts," as well as commissions on a gas deal with Israel and their roles in "mandatory partnerships with foreign companies in Egypt," the statement said. They were also being asked about "their role in privatization and evaluation of private shares and selling them," the prosecutor's office said.
Last month, Egyptians exulted over the detention of their ailing former president and his two sons in a probe exploring the killing of protesters in Cairo's Tahrir Square, the center of the country's dramatic uprising earlier this year that led to Mubarak's ouster.
Mubarak and his two sons were detained in connection with the protesters' deaths, an official with Egypt's Justice Ministry said at the time. Prosecutors have also been investigating what properties and bank accounts the Mubaraks have.
Hosni Mubarak has decried accusations of responsibility in the deaths, saying the probe is aimed at tarnishing his reputation and that of his family. He has also said he and his children have not violated any laws, and that an investigation of the properties they own will show they've done nothing wrong.