William Hague has blamed Bashar Assad's regime for the breakdown of Syria peace talks.
The Foreign Secretary said the lack of progress during the second round of discussions with rebels in Geneva was a "serious setback".
UN mediator Lakhdar Brahimi said the regime's refusal to countenance a transitional governing body was a major sticking point. No date has been set for more talks to end the conflict, which is thought to have claimed 100,000 lives over the past three years.
Mr Hague said: "The failure to agree an agenda for future rounds of talks on the Geneva process is a serious setback in the search for peace in Syria, and the responsibility for it lies squarely with the Assad regime.
"Lakhdar Brahimi's comments at his press conference this morning made clear that the regime refused to discuss the issue of a Transitional Governing Body, an issue that is at the heart of the negotiation and an essential means of ending the conflict.
"This cannot be the end of the road. With the war in Syria causing more death and destruction every day, we owe it to the people of Syria to do all we can to make progress towards a political solution.
"So we will continue to give our strong support to Lakhdar Brahimi and the Geneva process.
"It is also now more urgent than ever to move forward with a UN Security Council Resolution that addresses the appalling humanitarian suffering in Syria.
"The people in Syria's besieged areas and the many parts of the country not receiving any aid cannot wait."