8.58am BST

Good morning and welcome to the Middle East live blog.

Here are today’s headlines:

Syria

• The Syrian National Coalition, the umbrella opposition group recognised by the west, has called on the UN security council to allow its inspectors in Cyprus to enter Syria to search for chemical weapons. “We have confirmed reports from a number of countries in the world that the Syrian regime used chemical weapons on a limited scale, but it is seriously preparing for repeat use on a large scale, and the world must act before a major disaster occurs, not afterwards,” the opposition said in a statement.

• Barack Obama has made his clearest threat yet of international action against Syria, if the US can confidently establish that Bashar al-Assad's government was responsible for the recent alleged use of chemical weapons in the country. However, speaking at the White House after days of ambiguous rhetoric from Washington, the president said that he did not yet believe there was sufficient evidence to trace the use of chemical weapons back to President Assad's government. Obama told reporters:

What we now have is evidence that chemical weapons have been used inside Syria. What we don't know is who used them. We don't have a chain of custody. Without evidence of what happened, how can I make a decision what to do? I have got to make sure I have got the facts. If we rush to judgment without hard evidence we will find ourselves in a position where we cannot mobilise the international community for what we have to do. It is important that we do this in a prudent way.

But he also hinted that any use of chemical weapons would be a “game-changer”. The New York Times reported he was considering arming the rebels. Targeted missile strikes and a no-fly zone are also possible options, according to the Associated Press.

• Five people have been killed in fighting across Syria so far this morning, according to the Local Co-ordination Committees activist group. The group said that 173 people were killed yesterday, including 53 in Hama and 49 in Damascus. Their reports cannot be confirmed because media access to Syria is limited.

• Hassan Nasrallah, the leader of Hezbollah, has confirmed for the first time that members of the powerful Lebanese Shia organisation are helping President Bashar al-Assad fight the uprising against his rule – and will stand by him. Nasrallah – a close ally of Assad – also hinted that Russia and Iran, Syria's principal supporters, would intervene militarily to prevent his defeat. Hezbollah fighters have been seen in Syria helping the government from early on in the 25-month uprising but their presence, long formally denied, has become much both more open and large-scale in recent weeks, and funerals of fighters killed there are now a regular occurrence in Lebanon. The Syrian National Coalition opposition group called for the Lebanese government “to stop turning a blind eye” to Hezbollah’s “intervention” in Syria.

• A bomb killed 13 people yesterday near the former interior ministry in central Damascus, according to state TV and activists. State-run Suriya television said 70 people were wounded, several critically. The British-based Syrian Observatory reported nine dead civilians and three security personnel but said the toll was likely to rise. The bombing came a day after an apparent assassination attempt against prime minister Wael al-Halki.

• Violence in Syria has made even the Gaza Strip an attractive option for some – putting strain on its infrastructure, reports Harriet Sherwood in Beit Lahiya.

Israel

• Violence erupted on Tuesday in both Gaza and the West Bank, with the assassination by Israel of a militant bomb-maker and the killing of a Jewish settler, actions which are likely to complicate a drive by the United States to bring both sides back to negotiations after a four-year impasse.

Iraq

• Iraqi officials say a car bomb in a Shiite suburb of Baghdad has killed four people and wounded 12 others. Two police officers told AP the parked car bomb went off early on Wednesday morning in Hussainya and killed four civilians. They added that 12 others, including four policemen who were in a nearby checkpoint, were wounded.