The jihadist Islamic State group took control of the rebel-held half of the eastern Syrian city of Deir Ezzor on Monday, buoyed by advances in neighboring Iraq, a monitoring group said.

Rival rebel groups fighting forces loyal to President Bashar Assad either gave in and joined the IS or fled from the strategic Euphrates valley city, the Syrian Observatory for Human Rights said.

Jihadist militants publicly executed four Syrian men in a western Iraqi town for allegedly spying for President Bashar Assad's regime, witnesses and a doctor said on Monday.

Militants flying the flag of the jihadist Islamic State (IS) group brought the men to a main street in Al-Qaim, near Iraq's border with Syria, in a convoy of trucks on Sunday, witnesses said.

U.S. Attorney General Eric Holder said Sunday that intelligence suggesting bomb makers from Yemen have teamed up with militants in Syria was "more frightening than anything" he had seen before.

In an interview with ABC television's "This Week," Holder called the alleged cooperation between expert bomb-makers in Yemen and jihadists fighting in Syria's civil war a "deadly combination."

A rocket fired from Syria hit the Israeli-occupied sector of the Golan Heights on Sunday, falling on open ground and causing no casualties, an Israeli army spokeswoman told Agence France Presse.

"The assumption is that it was not a stray," she said, although there was no immediate report of Israeli retaliation.

U.S. Attorney General Eric Holder said on Sunday that intelligence suggesting Islamist bombmakers from Yemen have teamed up in Syria is "more frightening than anything" he had seen before.

In an interview with ABC News, Holder called the alleged cooperation between expert bomb-makers in Yemen and jihadists fighting in Syria's civil war a "deadly combination."

The head of Nigeria's Boko Haram Islamists has voiced support for the extremist Sunni Islamic State (IS) militants who have taken over large swathes of territory in Iraq and Syria, in a video obtained by Agence France Presse Sunday.

In the 16-minute video, given to AFP through similar channels as past messages, Boko Haram chief Abubakar Shekau also claims responsibility for a June 25 bombing in the capital Abuja and an attack hours later in Lagos which the authorities tried to cover up

Greece's coastguard on Sunday said four people had been confirmed drowned in the latest boat sinking in the Aegean Sea, while around 100 migrants had been rescued in other incidents.

The coastguard said it had recovered the bodies of a man and a young boy of around 10, part of a group of over 30 people whose boat capsized as they tried to reach the island of Samos on Friday.

A Syrian rebel commander was shot dead in Amman in an apparent revenge killing by family members, Jordanian police said Sunday as the opposition blamed the Damascus regime for his death.

Maher Rahhal, who headed the Liwa al-Mujahideen Brigade, one of the groups fighting to topple Syrian President Bashar Assad, "was shot twice in Abu Nseir district" late Friday, a security official said.

The United Nations Security Council is set to adopt a resolution Monday authorizing humanitarian convoys to serve millions of Syrian civilians by traveling from neighboring Turkey, Jordan and Iraq.

After weeks of negotiations, Australia, Jordan and Luxembourg drafted the text for a vote. Damascus's ally Russia, which has already used its veto on four Syria-related resolutions since the conflict began in March 2011, has no plans to do so this time.

Saudi Ambassador to Lebanon Ali Awadh Asiri revealed on Sunday that the body of the Duroy Hotel bomber was buried in al-Qassim Province in the kingdom, while his accomplice is "in good health."

“The body of Ali Ibrahim al-Thwaini was handed over to his family in al-Qassim province (in Saudi Arabia) where he was buried on Friday,” Asiri said in comments published in the Saudi daily Okaz.