President Mohammed Morsi on Wednesday stressed Egypt's commitment to freedom of expression, insisting his office was not behind a probe against a popular satirist that has raised international concerns.

"The presidency reiterates the importance of freedom of expression and fully respects press freedom," Morsi's office said in a statement.

Students stormed the gates of the Cairo headquarters of Egypt's Islamic al-Azhar University on Tuesday after hundreds suffered food poisoning at a dormitory, security officials said.

The protest took place as President Mohamed Morsi visited students hospitalized after eating contaminated food on Sunday evening, with the health ministry saying hospitals in the capital were treating 561 students.

Egypt's prosecution is probing complaints of "threatening public security" against popular satirist Bassem Youssef, who is already on bail facing charges of insulting the president and offending Islam.

Judicial sources and Youssef said the public prosecutor ordered the probe on Monday following a complaint by a lawyer. The state security prosecution, which handles national security cases, will conduct the investigation.

Cash-strapped Egypt on Monday hiked the price of subsidized cooking gas by 60 percent, triggering market chaos, officials and media reported, ahead of a visit by the IMF for talks on a $4.8-billion loan.

Ahram Online quoted an official from the domestic trade and supply ministry as saying the price of subsidized standard gas cylinders had been set at eight dollars ($1.15), from five pounds ($0.73) previously.

The United States on Monday voiced concern over freedom of expression in Egypt following the arrest of a comedian for allegedly insulting President Mohamed Morsi and Islam.

U.S. State Department spokeswoman Victoria Nuland said the detention and release of television satirist Bassem Youssef was evidence of a "disturbing trend" of mounting restrictions on freedom of expression.

Cairo's international airport will be partly closed at night due to fewer incoming flights and to save energy, reports said on Monday, highlighting the economic crisis sweeping Egypt.

Two runways will be closed for four hours starting from 1.30 am (2330 GMT) "in order to save energy", said civil aviation minister Wael al-Maadawi in statements carried by the press.

Egyptian satirist Bassem Youssef was released on bail on Sunday after nearly five hours of questioning over alleged insults to the president and religion, highlighting concerns over freedom of expression in post-revolt Egypt.

Youssef, whose weekly program Albernameg (The Show) has pushed the boundaries of local television with its merciless critique of those in power, was ordered to pay 15,000 Egyptian pounds (around $2,200) pending investigation into the complaints, judicial sources told Agence France Presse.

Gaza's Hamas prime minister Ismail Haniya headed to Cairo on Saturday to discuss his Islamist movement's complaints about Israeli compliance with an Egyptian-brokered truce.

Hamas spokesman Taher al-Nunu said Haniya would be discussing "Israeli violations of the truce," which ended eight days of deadly violence in and around the Gaza Strip last November.

Egypt's public prosecutor on Saturday ordered the arrest of popular satirist Bassem Youssef over alleged insults to Islam and to President Mohamed Morsi, state news agency MENA reported.

Judicial sources told Agence France Presse that several complaints had been filed against Youssef, whose razor-sharp humour -- delivered on his weekly television programme Albernameg (The Show) -- has spared few public figures.

The first direct flight connecting Egypt and Iran in more than 30 years took off from Cairo International Airport on Saturday, airport officials told Agence France Presse.

The Air Memphis plane, chartered by Egyptian businessman Ramy Lakah, is the first direct flight between the capitals since the two countries severed ties after Iran's 1979 Islamic revolution.