Britain must be prepared to go to war if it wants to end the conflict in Syria and keep chemical weapons out of the hands of al Qaeda, the outgoing head of the armed forces has warned.

General Sir David Richards, who steps down today as Chief of the Defence Staff, said that if the West wanted to see an end to President Bashar al Assad's regime it would have to step in as in it did to end the Gaddafi regime in Libya.

He also warned that if the regime suddenly collapsed then Britain "would have to act" to prevent chemical weapons falling into the hands of terror groups.

His comment were backed by the Defence Secretary, Philip Hammond, who said that no option was being taken off the table when it came to Syria.