Overseas Egyptians started voting Friday for a new president after the fall of ex-President Hosni Mubarak in February 2011.

An estimated 586,000 Egyptians abroad in 166 countries are expected to cast their ballots in the week-long voting, which will end on May 17. Nearly half of the overseas Egyptian voters, or 260, 000 people, are in Saudi Arabia.

The voting began after the first presidential debate was held between Amr Moussa and Abu El Fatouh, two forerunners in the presidential race with a total of 13 candidates.

The debate, aired live by two private TV channels on Thursday evening, was the first of its kind in Egyptian history.

In the argument, Fatouh tried to link Moussa to the Mubarak regime. Moussa was Egypt's foreign minister from 1991 and 2001 and then served as secretary general of the Cairo-based Arab League from 2001 to 2011.

Moussa refuted Fatouh's words, saying that he left Mubarak's regime in 2001 and was not part of it. Moussa asked about the relationship between Fatouh and the Muslim Brotherhood, saying that Fatouh was still a member of the group.

Fatouh was expelled from the Muslim Brotherhood after he announced his intention to run in the presidential polls last year, which violated the group's previous promises of not nominating any presidential candidate.

The two figures also debated on topics of foreign relations, health care, subsidy policy, wages and military budget.

Fatouh said he would build a democratic country based on the Islamic Sharia principles. Moussa stressed respect for the will of the people.

Both agreed to review the relations with Israel, which have seen turbulences since last year, especially after Egyptian protesters stormed the Israeli embassy in Cairo. Fatouh went further to say that Israel is an enemy.

Moussa has gained the support of the liberal Wafd Party. The Salafist Nour Party, which has one-fifth of the parliament seats, supports Fatouh.

According to polls, Moussa and Fatouh have been the top two popular candidates.

The presidential vote is set to be held on May 23 and May 24. A run-off will be held in mid June if no one wins in the first round.