British troops could be deployed to intervene in Syria in the event of a major humanitarian crisis, the head of the armed forces said today.
General Sir David Richards, the Chief of the Defence Staff, said contingency plans were being drawn up in case the onset of winter saw a worsening of conditions on the ground.
He indicated that any intervention would be limited and would need the support of people inside Syria in the areas where assistance was being provided.
Nevertheless such a move would be seen as a potential step towards a full-scale military intervention bringing British forces directly into conflict with the regime of president Bashar Assad.
"It would be a huge effort. We would be very cautious about it," he told BBC1's The Andrew Marr Show.
"There is no ultimately military reason why one shouldn't and I know that all these options are quite rightly being examined. but we are some way off."
He said he expected the humanitarian situation to deteriorate over the winter which could lead to calls to intervene "in a limited way".
"Obviously we develop contingency plans to look at all these things. It is my job to make sure that these options are continually brushed over to make sure that we can deliver them and they are credible," he said.
"The main thing for now that we are all focusing on is to contain the crisis so that it doesn't spill over into countries like Lebanon, Jordan, Turkey.
"That's our primary focus but that would also accommodate a humanitarian crisis because we could help deal with that through that primary mechanism. It is certainly something we have got to look at.
"We are keeping our awareness levels very high and in the meanwhile we are preparing plans to make sure that when some disaster happens we are able to deal with it."
He said that it was up to political leaders internationally to decide what the next steps should be.
"The international community and the political leaders need to decide what they want to do and then people like me can develop plans to meet those requirements. At the same time the people inside Syria must agree," he said.
His intervention comes amid growing signs of frustration in Downing Street at the inability of the international community to halt the fighting which has led to tens of thousands of deaths.
Following a visit last week to the region by David Cameron, officials made clear that they were looking at all options including the possibility of supplying arms to the anti-Assad rebels.