/> The US President Barack Obama and British Prime Minister David Cameron say the use of chemical weapons in Syria – or even a threat to deploy them – would be “completely unacceptable”.

In a phone call tonight – the two leaders agreed that if President Bashar Assad made such a move,  it “would force them to revisit their approach so far”.

They also say they have “much more to do” to stop the brutal killing of civilians in the Middle East state.