By Jo-Anna K. Burnett

Deployment of British troops is unlikely in the event of an international intervention in Syria, David Cameron has said.

US and UK officials have indicated limited but growing evidence exists that Syria currently possesses chemical weapons.

"It is very disturbing what we're seeing," Cameron told BBC Breakfast this morning.

"It's extremely serious. This is a war crime and we should take it very seriously."

He said the government was taking time to consider, analyse and verify information, rather than rushing to take action quickly.

When pressed on whether UK troops could be deployed to the region, Cameron added: "I don't want to see that and I don't think that is likely to happen."

But the prime minister called on the international community to "form a red line" on the issue, a term used to describe unacceptable actions like chemical and nuclear weapon production by countries.

He said he wanted to step up the pressure against Syria, potentially intensifying the trade embargoes, sanctions and travel restrictions that are already in place.

Strategies may include working with allies and helping to shape, train and mentor the opposition to bring Bashar al-Assad's regime to an end. Assad has been president of Syria since 2000.

"It is extremely difficult and extremely frustrating," said Cameron, who added that evidence-gathering will continue along with sending a clear warning to Syria.

Chuck Hagel, US defence secretary, said yesterday the intelligence community has assessed with some degree of confidence that the Syrian regime has used chemical weapons on a small scale, specifically sarin gas.

The origin of the weapons has not been confirmed, but Hagel said that he believes it originated with the current regime.