The probe does not necessarily mean charges will be leveled but it is unusual for state prosecutors to investigate such broad charges against high profile figures. The official spoke on condition of anonymity in line with government policies.
Yara Khallaf, a spokeswoman for Moussa, said there were no official charges or summoning for investigation, declining to comment on the accusation.
Emad Abu Ghazi, the secretary general of the opposition party ElBaradei heads, said he had no details about the investigation but that the accusations and probe were "an indication of a tendency toward a police state and the attempt to eliminate political opponents."
Abu Ghazi said the former regime of Mubarak dealt in the same way with the opposition. There was no immediate comment from ElBaradei or Sabahi.
The accusation came during a political crisis over a series of presidential decrees that granted Morsi, Egypt's first elected president, and the committee drafting the disputed constitution immunity from judicial oversight.
The opposition called on Morsi to rescind his decrees and accused him of amassing too much power in his hands. It also asked for the draft constitution to be withdrawn.
The opposition organized a number of massive rallies in protest, including one outside Morsi's palace in which protesters chanted "Leave." It was a common refrain during the protests against former President Hosni Mubarak, who was ousted in a popular uprising last year.
The rally turned violent when supporters of Morsi, who perceived the protest as a threat to his legitimacy, attacked their opponents.
Clashes erupted that turned deadly and were followed by attacks on offices of the Muslim Brotherhood, the main backers of the constitution and from which Morsi hails, and the office of a liberal opposition party, al-Wafd. At least 10 people died in the violence, and the Brotherhood claimed they were mostly its supporters.
Morsi and Brotherhood officials accused the opposition of working to undermine the president's legitimacy, and accused former regime officials of working to topple him.
Mubarak once again in hospital
Cairo • Egypt's deputy interior minister says that ousted President Hosni Mubarak has been transferred to a military hospital from his prison cell for the second time in a week following complications from a recent injury.
Mubarak is serving a life term after being sentenced in June for failing to stop the killing of hundreds of protesters during last year's uprising.
Maj. Gen. Mohammed Ibrahim said Thursday that the 84-year old Mubarak had been moved to the hospital in Cairo's Maadi suburb after reports showed his condition was deteriorating and he needed more attention.
Mubarak was hospitalized last week for X-rays of his head and ribs after he fell in a prison bathroom. His lawyers have asked authorities to return him to the hospital, which had better facilities than the prison.
The Associated Press