"The failure to agree an agenda for future rounds of talks ... Is a serious setback in the search for peace in Syria, and the responsibility for it lies squarely with the Assad regime," Hague said in a statement.
A second round of peace talks broke off today without making any progress and without a date being set for a third round, UN mediator Lakhdar Brahimi told reporters in Geneva.
But Hague said "this cannot be the end of the road."
"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," Hague said.
The opposition has insisted that the focus of the talks must be on creating a transitional government, without Assad. The regime representatives have meanwhile stubbornly insisted that Assad's position is non-negotiable.