The appeals court has ordered the reinstatement of the country's top prosecutor Abdel Maguid Mahmoud, sacked by Mursi in November. The court also cancelled Mursi's decision to appoint a new prosecutor general Talat Ibrahim.
Mursi's removal of Mahmoud angered senior judges, who saw it as an attack on their authority, the BBC reported.
The sacking was one of Mursi's first moves after issuing a decree granting himself sweeping new powers.
However, he kept in place his new appointment as prosecutor general.
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The incumbent prosecutor, Mahmoud, had been appointed by ousted former President Hosni Mubarak.
In December, amid outrage over his appointment, Ibrahim made, and then retracted, an offer to resign.
Meanwhile, Mursi, speaking to the Egyptian community in Doha, said that he expected parliamentary elections would be held in October and that the parliament would be in session before the year's end.
The Shura Council is expected to finalise the parliamentary elections law for referral to the Supreme Constitutional Court to see whether it is constitutional, Mursi was quoted by the MENA news agency as saying.