Assailants stormed about 500 demonstrators at dawn, many of them supporters of Hazem Salah abu Ismail, an ultraconservative Islamist preacher recently disqualified from the presidential race. Police did not intervene for hours, and authorities said as many as 200 people were wounded in the nation's worst violence in months.

Over the last year, Israel has scrambled to offset declining deliveries from Egypt by increasing its domestic production, but energy officials warn that a complete termination of supplies from Egypt may lead to power disruptions this summer.

The deal also provided much-needed revenue to Egypt, whose economy has been sinking since its tourism industry collapsed after last year's violence and instability.

Egypt's election organizers reinstated the presidential candidacy of former Prime Minister Ahmed Shafik on Wednesday, a day after excluding him from the race under a law banning top officials of deposed President Hosni Mubarak.

The state-run Middle East News Agency said the presidential electoral committee had accepted an appeal from Shafik challenging the panel's decision Tuesday that he was ineligible to run for the presidency in elections that begin next month.

Egypt's former Prime Minister Ahmed Shafik became the latest presidential hopeful to be disqualified by the Supreme Electoral Committee under a new law barring top officials in Hosni Mubarak's toppled regime from running for office, the state news agency MENA reported Tuesday.