Syrian rebel fighters have alleged that the Assad regime launched "a series of chemical attacks" on the Damascus suburbs of Adra and Douma yesterday morning.
Video posted on YouTube purports to show victims suffering from a range of symptoms associated with chemical weapon use.
ITV News cannot independently verify the social media content.
The use of chemical weapons is banned under the Geneva protocol.
More top news
It will be a cloudy and at times damp morning across much of the UK, apart from the far west where it will be dry and bright.
Barack Obama has returned to the political spotlight, campaigning for Democratic candidates ahead of upcoming elections.
The prime minister said there was a "clear and urgent imperative" to give new impetus to stalled negotiations.