ISMAILIA, Egypt (Reuters) - Egypt's interior minister sacked the head of North Sinai security on Sunday to try to restore order in al-Arish, security sources said, a day after three policemen were killed there and their colleagues protested they were not properly equipped.

Since Hosni Mubarak was ousted in a popular uprising in 2011, Islamist militants in Sinai have stepped up attacks on security forces in the region near the Israeli border.

Egypt's Islamist president, Mohamed Mursi, has pledged to restore security in the area. Israeli officials, already worried at having an Islamist in charge of nation with which they signed a peace deal in 1979, have voiced concern about lax security.

During the protest, police blocked a main highway linking al-Arish and the town of Rafah bordering with Gaza, prompting the ministers of defense and interior to visit the city and meet officials there to resolve the impasse.

General Samih Bishady took over from General Ahmed Bakr as the head of the security department on Sunday, the sources said. The state news agency also announced the decision by Interior Minister Ahmed Gamal el-Din to replace the security chief.

Army units were deployed around the police station over fears militants could launch more attacks or try to steal weapons from the station, one security source said.

Egyptian authorities have been searching for armed militants since the ambush and killing of 16 border guards on August 5. The government sent troops backed up by tanks, armored vehicles and helicopters to raid militant hideouts, arrest suspects and seize weapons in the biggest security operation in Sinai.

Efforts to impose central authority in the lawless desert region are complicated by the indigenous Bedouin population's ingrained hostility to the government in Cairo.

(Reporting by Yusri Mohamed; writing by Tamim Elyan; editing by Philippa Fletcher)