(Reuters) - A militant Islamist leader in Egypt's Sinai Peninsula was shot dead on Friday by unknown assailants, security sources said, a few days before Egyptians vote for a new president.

Egypt launched a wide-ranging campaign against militants in the Sinai after they stepped up attacks on police and army targets following the overthrow of elected President Mohamed Mursi, an Islamist, by the military last July.

The security sources said Shadi al-Menei and five others were killed in a firefight on the street in Maghara in central Sinai.

Al-Menei was the head of Ansar Beit Al Maqdis, or Defenders of Jerusalem, which was responsible for several recent attacks on security forces in Egypt.

A statement on the army spokesman's official Facebook page said the army had carried out an operation that resulted in the killing of six "extremely dangerous criminal elements" on Thursday. It did not name Menei and it was not immediately clear if the statement was referring to the same incident.

Separately, a security officer was shot dead by unidentified gunmen at a security checkpoint in the North Sinai town of Rafah, near the border with Israel, state news agency MENA reported early on Friday.

In Fayoum, southwest of Cairo, one man was killed and three others wounded in clashes between security forces and supporters of the Muslim Brotherhood, a medical source told Reuters.

Another person was killed in protests in Cairo and 20 others wounded, the health ministry said in a statement carried by the state news agency.

Egypt is gearing up for elections next week which former army chief and presidential candidate Abdel Fattah al-Sisi, who spearheaded Mursi's ouster, is widely expected to win.

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