Syria shipped out a fourth consignment of chemical weapons for destruction Wednesday but the international watchdog urged swifter progress towards a missed turn-of-the-year deadline to surrender the most dangerous agents.

The mustard gas loaded onto a cargo ship in the Mediterranean port of Latakia was one of five "priority chemicals" in Syria's arsenal which it was supposed to have handed over by December 31 under a disarmament deal approved by the U.N. Security Council last August.

U.S. Secretary of State John Kerry on Wednesday renewed allegations against Russia of helping the Syrian regime, accusing Moscow of increasing its aid to President Bashar Assad.

What Assad "is doing is outrageous, unconscionable, unacceptable, disgraceful, craven, it's horrendous. And we all know that. Everybody knows that," Kerry said.

Qatar's foreign minister said Wednesday his country and Iran both back a "political solution" to the conflict in Syria despite their support for opposite sides.

"Everyone is agreed on one point, that the Syrian crisis should be resolved through a political solution," Foreign Minister Khaled al-Attiyah told a joint news conference in Tehran with his Iranian counterpart, Mohammad Javad Zarif.

Some 3,300 people have been killed in fighting between rebels seeking President Bashar Assad's ouster and their erstwhile jihadist allies since clashes erupted in January, a monitoring group said Wednesday.

"Some 3,300 people have been killed ever since the start of fighting on January 3 between the (jihadist) Islamic State of Iraq and the Levant (ISIL) on one side, and (rebel) Islamist and other groups on the other," said the Syrian Observatory for Human Rights.

More than 170 Islamist rebel fighters, including Saudis, Qataris and Chechens, were killed Wednesday in a Syrian army ambush near Damascus, state news agency SANA reported.

The attack, apparently the deadliest against the rebels for months, took place in Eastern Ghouta, a key rebel stronghold targeted in a chemical attack in August 2013 that killed hundreds of people.

The Italian navy said on Wednesday it had rescued nearly 600 migrants crossing the Mediterranean from Africa over the past 24 hours in an operation launched after two shipwrecks in which hundreds drowned.

"The Navy has rescued 596 migrants on six vessels," including three rubber dinghies, it said in a statement.

Bahrain moved Wednesday to deter citizens from joining Islamist fighters abroad following similar action by other Gulf countries aimed at stemming the flow of homegrown jihadists to Syria.

The ministry said it has proposed an amendment to its anti-terror law, which currently prescribes a maximum five-year sentence for fighting abroad, pledging "more deterrent measures against citizens committing or taking part abroad in mass violence or combat."

Hizbullah may begin targeting Israeli officials in retaliation against Monday's Israeli strike against a party target near the Lebanese-Syrian border, reported Israel's Haaretz daily on Wednesday.

The party may begin targeting senior Israeli officials, sources told the daily.

A reported Israeli air raid on Hizbullah near the Lebanese-Syrian border on Monday evening would be the latest of several aimed at preventing arms transfers to the group, a key ally of Syrian President Bashar Assad:

--2013--

Russia on Tuesday warned Saudi Arabia against supplying Syrian rebels with shoulder-launched missile launchers, saying such a move would endanger security across the Middle East and beyond.

The Russian foreign ministry said in a statement that it was "deeply concerned" by news reports that Saudi Arabia was planning to buy Pakistani-made shoulder-launched surface-to-air missiles and anti-tank systems for armed Syrian rebels based in Jordan.