Egypt's ousted and jailed Islamist President Mohammed Morsi refused to answer a prosecutor's questions about allegations that he leaked classified documents — some related to the army's budget— to Qatar via the Doha-based Al-Jazeera broadcaster, Egypt's official news agency MENA reported Thursday, Aug 28, according to the Associated Press.

If the charges are referred to court, it would be the fourth case underway against Morsi, who was overthrown by the military last summer amid mass protests against his yearlong rule.

Morsi reportedly refused to answer any of the prosecutor's questions during a four-hour interrogation session held inside Borg al-Arab prison, near the Mediterranean city of Alexandria.

Morsi and other individuals are accused of passing state security files to Qatar, a close ally of his Muslim Brotherhood group, "in a way that harms national security," judicial officials said late Wednesday.

Egypt's General Prosecutor Hisham Barakat ordered Morsi and seven other detainees held for 15 days in reference to the case, the officials said, adding that other suspects remain at large. The officials spoke late Wednesday on condition of anonymity because they are not authorized to talk to reporters.

Morsi already faces charges of conspiring with foreign groups, inciting the murder of his opponents and orchestrating prison breaks during the 2011 uprising that toppled his predecessor, Hosni Mubarak.

Authorities claim to have uncovered a network of top Egyptian officials affiliated with the Muslim Brotherhood, Al-Jazeera employees and high-ranking Qatari officials who leaked the information and tried to smuggle the original documents. Officials said the network intended to sell the original documents to Qatar for $1.5 million.

MENA said some of the documents included information about the army's secretive budget, a sensitive issue in Egypt. It added that Al-Jazeera network already aired some of the leaked documents.

According to MENA, authorities found the original documents in three large suitcases.

The Muslim Brotherhood won a series of electoral victories after the 2011 uprising that toppled Mubarak, culminating in Morsi's election the following year, when he became the country's first freely elected leader. His year in power proved divisive, however, and the military toppled him following massive protests demanding his resignation.