Diaa told state-run television that 57 people had died in the accident, but AFP new agency, citing an official, reported 55 bodies were recovered.
The bus was travelling on a narrow road when it veered off the road into the Ibrahimiya Canal, near the village of Bahrut about 200 kilometres from Cairo.
On Monday, fifteen students were killed when a bus overturned on its way from Minya to Alexandria.
Egyptian roads are considered highly dangerous, with thousands of accidents every year. Regulations are not fully enforced and vehicles are badly cared for.
About 6,000 people die and 30,000 are injured in road accidents in Egypt annually.