David Cameron attacks UN for inaction on Syria

Prime minister tells general assembly that blood of Syrian children is 'terrible stain' on reputation of United Nations

David Cameron has launched his strongest attack on the United Nations over its inaction on Syria, declaring that the blood of young children is a "terrible stain" on its reputation.

In a display of Britain's impatience with Russia and China, which have blocked a series of UN security resolutions on Syria, the prime minister declared that "no one of conscience" could ignore the suffering.

Cameron, who was speaking to the UN general assembly shortly after the Iranian president, Mahmoud Ahmadinejad, cited a recent report by Save the Children which said that schools were being used as torture centres.

The prime minister said: "The blood of these young children is a terrible stain on the reputation of this United Nations. And in particular, a stain on those who have failed to stand up to these atrocities and in some cases aided and abetted Assad's reign of terror.

"If the United Nations charter is to have any value in the 21st century we must now join together to support a rapid political transition. And at the same time no one of conscience can turn a deaf ear to the voices of suffering."

The prime minister was not aiming his criticisms at the UN secretary general, Ban Ki-moon, who warned on Tuesday that the security council's failure to act on Syria could lead to "a regional calamity with global ramifications".

British officials said that on the diplomatic level the prime minister had in mind Russia and China, which have blocked attempts by Britain to agree tough UN security council resolutions condemning the regime of Bashar al-Assad. Tehran has a longstanding alliance with Assad while Britain recently stopped a Russian ship carrying helicopters to Syria by cancelling its insurance.

The prime minister, who called for the removal of Assad, said that his defenders were wrong to blame the Arab spring for the bloodshed. "Those who look at Syria today and blame the Arab spring have got it the wrong way round. You cannot blame the people for the behaviour of a brutal dictator. The responsibility lies with the dictator."

He said people who invested great hope in the Arab spring were also wrong to give up even in light of the bloodshed in Syria and the political uncertainty after the election of Islamist leaders in countries such as Egypt. Libya showed the mixed picture, the prime minister said, as he condemned the murder of the US ambassador Chris Stephens in a "despicable act of terrorism" while hailing elections to a new congress.

The prime minister said: "One year on, some believe that the Arab spring is in danger of becoming an Arab winter. They point to the riots on the streets, Syria's descent into a bloody civil war, the frustration at the lack of economic progress and the emergence of newly elected Islamist-led governments across the region.

"But they are in danger of drawing the wrong conclusion. Today is not the time to turn back, but to keep the faith and redouble our support for open societies, and for people's demands for a job and a voice."

Cameron won important support when Mohamed Morsi, the new Egyptian president, agreed with him on the need to step up pressure on China and Russia to secure a new UN security council resolution on Syria. In their first meeting Morsi told Cameron a new resolution should focus on sanctions, with the aim of isolating the Assad regime, because military action would worsen the crisis.

Cameron, who held his first meeting in New York with Morsi, believes that the performance of the first elected leader of the world's largest Arab country shows the progress made in the Arab spring. Morsi upset Iran when he used an appearance at the non-aligned conference in Tehran to criticise Ahmadinejad for taking the wrong side in Syria.

The prime minister used the example of Morsi to criticise former world leaders who wrongly tolerated dictators on the grounds that they guaranteed stability. "The fact is that for decades, too many were prepared to tolerate dictators like Gaddafi and Assad on the basis that they would both keep their people safe at home and promote stability in the region and the wider world. In fact, neither was true. Not only were these dictators repressing their people, ruling by control not by consent, plundering the national wealth and denying people their basic rights and freedoms, they were funding terrorism overseas as well."

Cameron did not name any former leaders. But Tony Blair embraced Muammar Gaddafi when he abandoned Libya's programme of weapons of mass destruction and was humiliated by Assad when he tried to reach out to Damascus in the wake of the 9/11 attacks.

In a dig at Blair and George W Bush, who had hoped that removing Saddam Hussein would unleash a new democratic Iraq, Cameron said his own approach was not "naive". He said: "I am not naive in believing that democracy alone has some magical healing power. I am a liberal Conservative, not a neoconservative."

The prime minister's tough language on Syria reflects Britain's exasperation with China and Russia, which are using their vetoes as permanent members of the UN security council to block new resolutions. Britain believes there is no hope of Moscow and Beijing giving any ground at the moment.

Officials talk of a "logjam" because the process launched by Kofi Annan, the former UN secretary general, has failed. The prime minister believes there are two parallel processes under way in Syria – moves, led by the likes of Annan, to encourage a political transition at the top and a bloody revolution bubbling from below that will take some time to lead to a political transition at the top.

Cameron would like the security council to agree to a new resolution under chapter seven of the UN charter, which authorises the use of force. This would provide legal authority for non-military intervention in Syria and could provide legal cover for military intervention at a later stage.

The prime minister believes that, in the highly unlikely event of a new security council resolution, military action would be unrealistic. No-fly zones and safe zones would involve military force that could not be delivered.

In his speech the prime minster announced that Britain was to provide £3m for a Unicef fund to help 500,000 refugees in Syria, more than half of whom are children, as winter approaches.