William Hague has condemned the reported killing of Syria's defence minister.
The Foreign Secretary said the apparent attack on defence minister Dawoud Rajha should pave the way for a new United Nations (UN) Security Council resolution.
Mr Hague was speaking amid claims Syrian president Bashar Assad's brother-in-law General Assef Shawkat, the deputy defence minister, also died in the bombing.
"We are aware of reports that the Syrian defence and deputy defence ministers have been killed, and a number of others injured, by an apparent suicide bombing in Damascus," Mr Hague said. "This incident, which we condemn, confirms the urgent need for a chapter VII resolution of the UN Security Council on Syria.
"The situation in Syria is clearly deteriorating. All the members of the UN Security Council have a responsibility to put their weight behind the enforcement of joint special envoy Kofi Annan's plan to end the violence.
"We call on all parties to refrain from violence and for the Security Council to shoulder its responsibilities."
A Chapter VII resolution would increase the pressure on President Assad's regime as opposition rebels close in on the capital.
If the resolution is agreed it could ultimately lead to military action, but Russia is tipped to veto an agreement.
Former foreign minister Lord Malloch-Brown said the attack was "an astonishing penetration of Syrian security", adding: "It will be a huge blow to their morale."
The peer, a former deputy secretary-general of the United Nations, believed the bombing would lead to a resolution, but told BBC Radio 4's World At One: "Whether or not it has a Chapter VII reference remains to be seen." He believed the Russians would see such a reference as "a foot in the door for potential force down the road".