An Israeli Bedouin who has been jailed in Egypt for more than 12 years on charges of spying has begun an open-ended hunger strike, he said in a handwritten letter in Arabic seen by Agence France Presse.

Ouda Tarabin's letter, passed on to the Israeli embassy in Cairo, was addressed to Ambassador Yaakov Amitai.

Apparent revenge attacks after clashes between protesters and Iraqi security forces entered a second day on Wednesday, killing 12 people, while three more died in other unrest, officials said.

The violence brings the toll since Tuesday to 84 dead, 66 of them in clashes and attacks involving security forces, protesters and their supporters.

Pope Francis called Wednesday for the release of two Syrian bishops kidnapped by gunmen near Aleppo, after a Christian group appeared to retract its claim that the clerics had been freed.

Aleppo's Greek Orthodox Bishop Boulos Yaziji and Syriac Orthodox Bishop Yohanna Ibrahim were kidnapped on Monday by armed men en route from the Turkish border.

A senior civil servant at Syria's electricity ministry was killed by a magnetic bomb attached to his car on Wednesday in central Damascus, state news agency SANA reported.

"As part of a campaign of assassinations... terrorists fatally wounded Wednesday morning Mohamed Abdel Wahab Hassan, the director of planning at the electricity ministry, with an explosive device attached to his car," SANA said.

Aleppo's Greek Orthodox archdiocese said Wednesday it had no news on two Orthodox bishops kidnapped in Syria, a day after a Christian association said the two men had been released.

"We have no new information," Ghassan Ward, a priest at the archdiocese, told Agence France Presse.

Syrian rebels battled regime troops inside the Minnigh military airport in the north of the country for the first time on Wednesday, the Syrian Observatory for Human Rights said.

"The rebels, who have laid siege to the airport for months now, entered it for the first time around dawn," Observatory director Rami Abdel Rahman told Agence France Presse.

U.S. Defense Secretary Chuck Hagel landed in Egypt on Wednesday as part of a Middle East tour designed to bolster America's alliances amid growing concern over the fallout from Syria's roiling civil war.

In his first trip to the Middle East as Pentagon chief, Hagel is promoting longstanding U.S. military ties with traditional allies -- including Israel and Saudi Arabia -- as a way of countering Iran and deterring Islamist militants.

An adviser to President Mohamed Morsi has submitted his resignation in protest at the running of the state and the "failure" of the government, Egyptian media announced on Tuesday.

"Mohamed Fuad Gadallah, presidential adviser on judicial affairs, is resigning," the public television channel Nile News said.

The United States has withdrawn a demand that the United Nations start human rights investigations in disputed Western Sahara following furious lobbying by Morocco, diplomats said Tuesday.

Morocco, which has occupied Western Sahara since the 1970s, had condemned a U.S. move to put the demand in a U.N. Security Council resolution on the U.N. peacekeeping mission in the North African territory to be voted on Thursday.

Bomb attacks on Sunni mosques in Iraq killed 13 people and wounded dozens of other people on Tuesday, security and medical officials said.

Two rounds of mortar fire hit a mosque in Muqdadiyah, northeast of Baghdad, killing nine people and wounding 25, police and a doctor said, revising an earlier casualty toll.