UAE air strikes on Libya aim to prevent Islamists from controlling the violence-stricken country and sends a message to Washington that it is capable of protecting its own interests, experts say.

United States officials said that United Arab Emirates warplanes secretly bombed Islamist militia targets in Libya from bases in Egypt last week, but Abu Dhabi has not publicly acknowledged involvement. On Tuesday, Egypt denied any "direct" role in the raids.

The United States said Monday that it had asked Qatar in advance not to pay a ransom for the release of U.S. hostage Peter Theo Curtis, who was freed by an Islamic rebel group in Syria.

The UAE armed forces, which U.S. officials say launched air strikes against Islamists in Libya, has 51,000 members, including 4,500 in the air force, the International Institute for Strategic Studies says.

The army has 44,000 personnel and the navy 2,500, the IISS says in its publication The Military Balance 2014.

Syrian war planes carried out a series of air raids Tuesday on positions held by the Islamic State jihadist group in eastern Deir Ezzor province, an NGO and state media said.

"Syrian army forces targeted headquarters and warehouses storing weapons and ammunition belonging to the terrorist group known as the Islamic State... destroying them completely," Syria's state news agency SANA reported.

Iran was the first country to provide Iraq's embattled autonomous Kurdish region with weapons to fight off jihadist-led militants, president Massud Barzani said on Tuesday.

"The Islamic Republic of Iran was the first state to help us... and it provided us with weapons and equipment," Barzani said at a joint news conference with Iranian Foreign Minister Mohammad Javad Zarif.

Saudi authorities beheaded a citizen in the eastern Qatif region on Tuesday after he was convicted of killing a fellow national, the interior ministry announced.

Mohammed al-Taroti killed Abdullah Abu Sarir by running him over in a car following a dispute, the statement published by the official SPA news agency said.

Islamist militias have distanced themselves from jihadists seeking Islamic law in Libya, saying they support a democratic transition, but they are also challenging the legitimacy of the newly elected parliament.

Fajr Libya (Libya Dawn) militiamen, who seized Tripoli airport from nationalist Zintan fighters on Saturday, said in a statement published by the LANA news agency Tuesday that they "respect the Constitution and the peaceful transfer of power".

Germany said Tuesday that one of its nationals had died in a tense region of Tunisia, after Tunisian officials said police had killed two women at the weekend, mistaking them for members of an armed group.

"The foreign ministry must unfortunately confirm that a German national was fatally injured in Kasserine in Tunisia," a ministry spokeswoman told AFP.

A car bomb ripped through a crowded Baghdad intersection during morning rush hour on Tuesday, killing 15 people and wounding at least 37, security and medical officials said.

The blast in Baghdad Jadida left a shallow crater at the intersection and lines of burned and twisted cars still sitting where they were waiting when the explosion struck.

Nineteen people were killed and 15 injured when two minibuses plunged into an irrigation canal in southern Egypt early on Tuesday, a health ministry official said.