Two election front-runners, a former foreign minister and a moderate Islamist, squared off Thursday in the Arab world's first ever presidential debate, trading barbs over the role of religion and how to bring democratic reform to Egypt.

Egyptians crowded around television sets in outdoor cafes for the four-hour debate, aired on several independent TV channels — a startling new experiment for Egypt after nearly 30 years of authoritarian rule under President Hosni Mubarak, ousted last year after a wave of protests.

For most of Mubarak's rule, he was re-elected in referendums in which he was the only candidate. The last presidential election, in 2005, was the first to allow multiple candidates, but Mubarak was considered a certain winner and campaigning was weak — and a direct debate was out of the question.

The debate, which ran well past midnight, pitted Amr Moussa, who served as Mubarak's foreign minister for 10 years until becoming head of the Arab League in 2001, against Abdel-Moneim Abolfotoh, a moderate Islamist who broke with the Muslim Brotherhood last year.