Iran said on Tuesday that it was holding the United States responsible for the lives of 48 of its citizens taken hostage in Syria, following an unconfirmed report by a Syrian rebel group that three of them had been killed by shelling.

The foreign ministry, which transmitted its message through the Swiss embassy in Tehran that handles U.S. interests in the absence of Iran-U.S. diplomatic relations, insisted the 48 were pilgrims, not Revolutionary Guards as the rebels claimed.

Israel has returned to Egypt the bodies of "between six and eight" gunmen involved in a deadly attack in northern Sinai who then forced their way over the Israeli border, a military spokesman said on Tuesday.

Speaking to AFP, he said that some of the bodies had been so badly torn apart by explosives that it was impossible to be sure how many there were.

The defection of Syria's prime minister shows President Bashar Assad has lost control of the country and that his people believe his days are numbered, U.S. officials said Monday.

Prime Minister Riad Hijab slipped across the border into Jordan on Sunday night and announced he was joining rebels in the highest-ranking defection of the 17-month uprising against Assad's rule.

Iran is to hold a ministerial meeting on Thursday for countries having a "realistic position" on Syria, Deputy Foreign Minister Hossein Amir Abdollahian said, the official news agency IRNA reported.

He said 10 countries would be participating, but did not identify them.

Egypt's army vowed Monday to "avenge" the killing of 16 troops by gunmen near the Israeli border, as President Mohammed Morsi ordered security forces to take full control of the Sinai Peninsula.

In Sunday's attack, 35 gunmen in Bedouin clothing opened fire on the troops before crossing into the Jewish state in an armored vehicle, Egyptian officials said. Israel said five gunmen were killed on its side.

Germany said Monday that the defection of Syrian prime minister Riad Hijab pointed to the rapid "erosion" of the regime of President Bashar Assad.

"The reports show how far the erosion process of the Assad regime has progressed," Foreign Minister Guido Westerwelle said in a statement.

Militiamen who sided with the Yemeni army in battling al-Qaida "arrested" four jihadists allegedly involved in a suicide bombing that killed 45 people over the weekend, a local official said on Monday.

"The Popular Resistance Committees, in cooperation with the army, arrested four al-Qaida members suspected of involvement in Saturday's suicide attack," local official Mohsen bin Jamila told Agence France Presse.

An overnight blast in southeastern Turkey interrupted oil flow from Iraq, a Turkish energy ministry official said Monday.

The blast hit the Kirkuk-Ceyhan pipeline in Mardin province close to Turkey's border with Syria and repairs are expected to take up to 10 days, the official added on customary condition of anonymity.

Israeli Prime Minister Benjamin Netanyahu on Monday expressed regret over the deaths of 16 Egyptian guards in an attack on Sunday by gunmen on the border with Israel, his office said in a statement.

It said that he was speaking during a visit with Defense Minister Ehud Barak to the site where five attackers crashed across the frontier in an armored vehicle into the Jewish state, where they were killed by Israeli forces.

The leader of the opposition Syrian National Council said the defection on Monday of Prime Minister Riyad Hijab showed the regime of President Bashar Assad is "disintegrating."

"We welcome the defection of Riyad Hijab and those of all the other civilian and military officials," Abdel Basset Sayda told AFP by telephone.