CAIRO – Egypt's public prosecutor Thursday ordered a probe into the top three leaders of the opposition on suspicion of trying to incite followers to overthrow President Mohamed Morsi, a legal source said. The prosecutor, Taalat Ibrahim Abdallah, who was appointed by Morsi late last month, signed the order against the leaders of the opposition National Salvation Front, which led protests against Morsi's drive to have a new constitution adopted. The probe targets Mohammed ElBaradei, a Nobel peace prize laureate, Amr Moussa, former chief of the Arab League, and Hamdeen Sabahi, the leader of the nationalist left wing. Moussa and Sabahi were presidential candidates in June elections that Morsi won. The National Salvation Front alleged frauds and irregularities in the Dec. 15 and 22 split referendum on the new charter, which Morsi signed into law this week. It accuses Morsi's Muslim Brotherhood of wanting to use the constitution to introduce creeping strict Islamic Shariah law. Abdallah called on Justice Minister Ahmed Mekki to name an investigating magistrate for the probe, which would examine suspicions of “inciting for the overthrow of the regime.” Morsi Wednesday hailed the adoption of the new constitution with 64 percent of the votes in the referendum, though turnout was a low 33 percent. Within two months, Egypt has to hold legislative elections to choose a parliament to succeed the one dissolved by the constitutional court in June. The opposition parties in the National Salvation Front coalition are considering competing in the elections on the same ticket. Meanwhile, cabinet sources said Thursday that Egypt's prime minister may replace as many as eight ministers next week as part of Morsi's plan to reshuffle the government ahead of a parliamentary election early next year. The reshuffle is likely to affect service ministries and possibly one ministry with an economics portfolio, the sources said. The service ministries that may be reshuffled include those of communications, transport, local development, electricity, petroleum, supplies, and internal trade, they said, adding between six and eight ministries were likely to be affected. Cracks in the Cabinet But cracks have already appeared in the Cabinet as an Islamist minister resigned Thursday, saying he disagreed with the slow pace of reform. It was the second resignation in Egypt's cabinet since Communications Minister Hany Mahmoud quit citing his “inability to adapt to the government's working culture.” Mohamed Mahsoub, a member of a centrist party which has recently backed Morsi, said he was resigning from his post as minister for parliamentary affairs because he believed the government needed to change more radically. Morsi had earlier said he would task Prime Minister Hisham Qandil, an independent technocrat, with making limited cabinet changes ahead of a parliamentary election in early 2013 but Mahsoub hinted he wanted Qandil himself to be removed. “I have reached a clear conclusion that a lot of the policies and efforts contradict with my personal beliefs and I don't see them as representative of our people's aspirations,” Mahsoub said in a resignation letter published on his Wasat Party's Facebook page. He added that Egypt needed “radically different policies and methods.” He also criticized the government's failure to recover funds allegedly embezzled by members of ousted leader Hosni Mubarak's regime. – Agencies