Responding to the murder of aid worker David Haines, Prime Minister David Cameron said:
This is a despicable and appalling murder of an innocent aid worker. It is an act of pure evil. My heart goes out to the family of David Haines who have shown extraordinary courage and fortitude throughout this ordeal. We will do everything in our power to hunt down these murderers and ensure they face justice, however long it takes.
A Downing Street spokesperson said:
The PM will chair a COBR meeting tomorrow morning.