The Associated Press reports: In northern Syria, the Observatory and another activist group, the Local Coordination Committees, reported intense clashes between government troops and rebels in the town of Maaret al-Numan, in Idlib province, on Sunday night.

The U.N. refugee agency said 230,000 Syrians have fled their homes since the uprising against Assad’s regime began last year. The U.N. says more than 7,500 people have been killed in the past 12 months.

Panos Moumtzis, the UNHCR’s coordinator for Syria said 30,000 people have already fled to Turkey, Lebanon and Jordan and “on a daily basis hundreds of people are still crossing into neighboring countries.”

Moumtzis said at least 200,000 people were also displaced within the country, according to the Syrian Arab Red Crescent.

BBC diplomatic correspondent Jonathan Marcus writes: Since the outset of the Syria crisis in March 2011 there has been little appetite for outside military intervention. This has been based on two assessments.

Firstly, that the situation on the ground in Syria is in many ways very different from that in Libya – the opposition is much more divided, the government’s security forces are much stronger, and Syria’s air defences are more effective.

Secondly, there has been a view that the implications of toppling President Bashar al-Assad could prompt a much wider wave of instability in the region.

Unlike Libya, Syria – both politically and geographically – is a central player in the Arab world, and sectarianism and instability there could threaten both Lebanon and Iraq.

Then, of course, there is the fundamental legal problem. Constrained by Russian and Chinese vetoes at the UN Security Council, there is no possibility of getting a resolution to authorise force.

That has not always mattered in the past. Nato troops went into Kosovo, after all, to halt systematic abuses by Serbian forces.

But the absence of legal authorisation certainly precludes action when there is little enthusiasm for it in the first place.

So what are we to make of calls from senior Republican politicians in the US, like Senator John McCain, urging air strikes against Syrian security forces?

Joshua Landis, director of the Centre for Middle East Studies at the University of Oklahoma, says: “Despite the growing chorus of politicians calling for US leadership in Syria, the Obama administration is adamant that Washington should not take the lead, but follow regional partners, Saudi Arabia and Turkey.”

Mr Landis argues that the simple fact is that the Obama administration sees no strong reason to intervene.

“US officials are unanimous in arguing that the Assad regime is doomed and can only hang on for a limited time, with or without increased US support for the Syrian opposition. I think they are right in this analysis.”

“This means that the US has no compelling national security interest in jumping into the Syrian civil war that is emerging. The regime’s days are numbered.”