CAIRO (AP) ― Egypt’s election commission disqualified 10 presidential hopefuls, including Hosni Mubarak’s former spy chief and fundamentalist Islamists, from running Saturday in a surprise decision that left a field of moderates in the race for the country’s first post-revolutionary leader.

The elimination of the three most powerful and controversial candidates could go in two directions with just weeks to go before the vote, observers said. It could plunge the Arab world’s most populous nation into a new political crisis, or just the opposite, defuse it.

Farouk Sultan, the head of the Supreme Presidential Election Commission that was appointed by Egypt’s military rulers to oversee the vote, said that those barred from the contest included Mubarak-era strongman Omar Suleiman, Muslim Brotherhood chief strategist Khairat el-Shater and hard-line Islamist Hazem Abu Ismail. He did not give reasons.

Disqualified candidates have 48 hours to appeal the decision, according to election rules. The final list of candidates will be announced on April 26.

The announcement came as a shock to many Egyptians as three of the 10 excluded were considered among the front-runners in a highly polarized campaign that has left the nation divided behind two strong camps: Islamists and former regime insiders who are allegedly supported by the ruling generals.

Thirteen others had their candidacy approved, including former Arab League chief Amr Moussa, moderate Islamist Abdel-Moneim Abolfotoh and former prime minister and Mubarak-era minister Ahmed Shafiq, according to Sultan.

If upheld, the decision would reshape the electoral landscape by removing the most powerful and controversial candidates and leaving moderates such as Abolfotoh, an ex-Muslim Brotherhood leader who has been trying to project crossover appeal for both religious conservatives and liberals, and Moussa, who was a member of the old regime but is popular among middle class Egyptians and who is not so closely associated with it.

The presidential election is due on May 23-24, with a possible runoff on June 16-17. The winner will be announced on June 21, less than two weeks before the July 1 deadline promised by the military rulers who took over after Mubarak to hand over power.

Abu Ismail, a lawyer-turned-preacher whose eligibility had come under scrutiny in recent weeks over the question of whether his late mother had dual Egyptian-U.S. citizenship, accused the military rulers who assumed power after Mubarak’s ouster of trying to manipulate the race from behind the scenes and warned his followers would not stay silent.

“You will drown, God willing, because you are in showdown with the people, because you are playing with fire,’’ he said in an interview with the Islamist TV network Al-Hakma.

Abu Ismail has led the most aggressive campaign so far. On the eve of the announcement, hundreds of his supporters surrounded the election commission’s headquarters in Cairo, forcing Sultan and his employees to evacuate under the military protection.

A new election law passed after Mubarak’s ouster bars an individual from running if the candidate, the candidate’s spouse or parents hold any citizenship other than Egyptian, and the commission had ordered the Interior Ministry to provide evidence showing whether Abu Ismail’s mother was officially documented in Egypt as having dual U.S. -Egyptian citizenship.

A spokesman for el-Shater’s campaign, Murad Mohammed Ali, also called the decision “very dangerous’’ and said it gives a message that “there was no revolution in Egypt.’’