President Abdel Fattah al-Sisi urged Egyptians Saturday to be patient in the face of power cuts, two days after a major disruption in Cairo, saying massive investment is needed to fix the problem.

Throughout the summer, Egypt has suffered power blackouts caused by rising demand for fans and air conditioning in the sweltering heat and by a shortage of fuel to run generating plants.

On Thursday, a huge power outage blacked out most of Cairo, causing major disruption across the city of some 20 million people at the height of the morning rush hour.

Addressing the situation, Sisi said the electrical power sector "needs colossal investment," adding that "we must all understand that this is not something that can be solved overnight."

He told people they must be patient regarding a problem that "has not been dealt with for several years."

Successive political crises since the early 2011 ouster of longtime president Hosni Mubarak have frightened off tourists and investors and brought the economy to its knees.

Power shortages were a factor contributing to massive street protests that led to the July 2013 ouster of Islamist president Mohamed Morsi by the military, headed at the time by Sisi.

Last month, the interior ministry said it had arrested 40 Morsi partisans, accusing them of carrying out attacks on electrical power infrastructure.