BBC News with Fiona MacDonald.

President Obama has promised a vigorous investigation into reports that forces loyal to the Syrian leader have used chemical weapons. Speaking during talks with King Abdullah of Jordan, Mr Obama repeated that proof of the deployment of chemical weapons would be, in his words, a game changer. However, he stressed that the intelligence assessments were preliminary.

"We are going to be working with countries like Jordan to try to obtain more direct evidence and confirmation of this potential use. In the meantime, I’ve been very clear publicly, but also privately, that for the Syrian government to utilize chemical weapons on its people crosses a line that will change my calculus and how the United States approaches these issues. So this is not an on or off switch. This is an ongoing challenge that all of us have to be concerned about.”

A United Nations envoy Martin Kobler has warned that Iraq is at a crossroads after a wave of violence, which has left more than 150 people dead since Tuesday. The fighting has raised fears of a return to wider sectarian conflict between minority Sunnis and the Shia-led government. Here’s the BBC’s Nahed Abouzeid.

The Iraqi government’s decision to act firmly to end the protests in Sunni areas has increased the level of tension in the country. Sunni leaders accused the army of committing a massacre when they stormed the protest camp in the town of Hawija. The Shia-led government says, however, that soldiers were attacked and acted in self-defence. And the latest violence in Baghdad, a series of attacks on Sunni mosques, caused many casualties and the protests by the Sunnis have continued since the start of the year in the Anbar district and show little sign of stopping.