Foreign Secretary William Hague has urged Russia to join diplomatic efforts to end the violence in Syria as he warned the United Nations had "failed" in its duty.
"The situation in Syria casts a long shadow over this debate," he said.
"In the eyes of the overwhelming majority of the world, this council has so far failed in its responsibilities towards the Syrian people."
Hague chaired a meeting of the UN Security Council on the so-called Arab Spring which is likely to be dominated by the ongoing bloodshed in Homs and other towns and cities.
Moscow - along with China - has twice vetoed resolutions calling on Syrian president Bashar Assad to step aside in a bid to end the year-long brutal repression of anti-government protests.
Russian foreign minister Sergei Lavrov is also due to meet for one-on-one talks with US Secretary of State Hillary Clinton amid continued disagreement over the approach to take.
The UN estimates that the violence has killed over 7,500 people.
Hague said the continued stand-off was "deeply frustrating".
"We want agreement on a United Nations Security Council resolution. A resolution that backs Kofi Annan, that backs the work of the Arab League, that calls for humanitarian access and an end to violence.
"It ought to be possible for the nations of the United Nations Security Council to agree a resolution which contains those elements.
"I will say in the debate that the United Nations Security Council so far has failed in its responsibilities. It does not mean in any way that we stop trying."
Hague said the UK remained of the view that it was very hard to see how anything other than the removal of Assad would satisfy the Syrian people.
Earlier the bodies of around 25 children and 20 women have been discovered in the devastated Syrian city of Homs.
Activists said that the bodies appeared to be victims of a "massacre" by government security forces.
The city has been subject to an assault by the Syrian army for weeks, and attacks have continued even after opposition forces withdrew under pressure from intense shelling.
The Activists News Association published extremely graphic videos on Facebook which appeared to show the corpses in a field hospital.
The latest gruesome discovery came after a weekend of diplomatic efforts by UN and Arab League special envoy Kofi Annan to secure terms for a ceasefire.
Annan said that he was "optimistic" following the talks, and that if enacted his "concrete proposals" could lead to a ceasefire, but critics said that President Assad had rejected all talks with "armed terrorist groups", meaning the increasingly militarised opposition movement, and had given no ground over his own personal hold on power.
The UN estimates that at least 7,500 people have died in Syria since the start of the uprising 12 months ago. Activists say that the total is closer to 10,000.
In Hague's statement at the UN he said:
The situation in Syria casts a long shadow over this debate.
In the eyes of the overwhelming majority of the world, this Council has so far failed in its responsibilities towards the Syrian people.
It has failed to address the brutal oppression of peaceful protesters by the Syrian regime, and it has not yet put its weight and authority behind the efforts of the Arab League.
It is time for the Security Council to show unity and to show leadership.
It should be possible for the Council to call for an immediate end to the brutal repression and violations of human rights;
- to demand an end to all violence and immediate and unhindered humanitarian access;
- to call on the Syrian government to implement its own commitments to the Arab League, by stopping military action, withdrawing its forces from towns and cities, releasing all political prisoners and allowing access to the media;
- to endorse the work of the Arab League and of Kofi Annan in his role as Joint Arab League and UN Envoy;
And to support UN and Arab League facilitation of a Syrian-led political transition. I call again on the Council to adopt a resolution containing these essential elements.
Beyond this Chamber, British experts are working in Jordan, Turkey and Lebanon to help document crimes against the Syrian people. I urge other nations here to join us in that effort, so that the regime knows it cannot proceed down this path with impunity.