William Hague has warned the UN that it risked causing a "catastrophe" if a deal is not struck on how best to deal with the on-going crisis in Syria during this week's summit.
The foreign secretary, speaking before the UN Security Council in Geneva, urged the group to draw up ceasefire proposals and create a path to peace for the war-torn country.
Hague told the Geneva summit on Saturday: "We face a heavy responsibility today.
"The world is looking to us for leadership and action to end the bloodshed and horror in Syria."
To not do so would "miss the opportunity to achieve a diplomatic breakthrough and watch the situation deteriorate further. The cost of any such failure would be counted by the people of Syria in lives lost and injuries sustained, livelihoods wrecked and suffering endured," Hague added.
While much of the UN seeks to have President Bashar al-Assad replaced with democratic rule, Russia believe that Syria, who remain one of Russia's few allies in the Middle East, should be the only country involved in deciding its fate.
This week's summit was preceded by talks between the US Secretary of State Hillary Clinton and Russia's Sergei Lavrov, in an attempt to work through the countries' differences on how to end the violence.
The summit comes as human rights groups call for urgent intervention in the Syrian city of Douma.
According to the London-based Syrian Network of Human Rights, forces loyal to President Assad raided the city, taking the lives of dozens of civilians, as well as targeting two hospitals.
"Volunteer doctors and paramedics fled to save their lives leaving behind scores of wounded citizens," the group claimed.
The Network called on the UN to reach a plan to help the city, supervising an evacuation from the city, which it says is surrounded and has been denied humanitarian aid.