The Telegraph reports: During a visit to Syria’s neighbour, Turkey, the US secretary of state, Hillary Clinton, said that America and Turkey were creating a formal working group to provide “very intensive operational planning” for the Syria crisis.

The group will coordinate military, intelligence and political responses to the potential fallout in the case of a chemical attack, which could result in huge numbers of casualties and a further influx of refugees into Turkey.

“We have been closely coordinating over the course of this conflict, but now we need to get into the real details of such operational planning. It needs to be across both of our governments,” Mrs Clinton told a news conference on Saturday after a meeting with the Turkish foreign minister, Ahmet Davutoglu.

Asked by a reporter if such discussions included imposing a no-fly zone to protect territory controlled by rebels, Mrs Clinton indicated that it was a possible option. “The issues you posed within your question are exactly the ones the minister and I agreed need greater in-depth analysis,” she said, although she said no decisions were imminent.