Leading article: Send in the United Nations

The already terrible situation in Darfur is deteriorating. The Janjaweed militia has resumed its attacks on civilians. Darfuri rebels have responded by targeting Sudanese government troops. A recent United Nations report estimates a further 200,000 black Africans have been forced to leave their homes in the past four months. The situation has been additionally complicated by rising tensions between Khartoum and the shaky government of neighbouring Chad.

The prospect of a genuine settlement between government and rebel forces seems as unlikely as ever. African Union mediators in the region have presented a draft agreement calling for peace and development to both sides at official peace talks in Nigeria. But seven rounds of talks have yielded nothing in the past.

It is also increasingly clear that the African Union force on the ground is unable to cope. We should not be surprised at this. The 7,000-strong troop deployment is under-equipped to monitor a road-less territory the size of France. And the April 2004 ceasefire they were originally called in to police was never really respected by either side.

The only viable solution at this stage is for a UN peacekeeping force to take over. The African Union's Peace and Security Council has agreed in principle to such a handover when its mandate ends in September, although the approval of the full AU is still required. The US is also pushing strongly for UN involvement.

Yet it will not be easy to get such a resolution through the Security Council. The Sudanese government opposes UN involvement in Darfur and is refusing to allow a UN mission to assess the situation. Without such a mission, there can no mandate for troop deployment. Summoning the will for action from the international community will be difficult, too. This is another poisonous legacy of the invasion of Iraq. There is little appetite in the West, outside the evangelical Christian right in America, for another open-ended military commitment. Khartoum's sabre rattling at the prospect of any foreign intervention is also a disincentive. A possible veto in the Security Council by China, hungry for Sudan's oil, must also be considered.

But a UN deployment is by no means impossible. The Security Council has already approved a 10,700-strong UN peacekeeping mission to monitor the agreement to end the civil war in the south of Sudan. This is an appropriate context in which to treat Khartoum's noisy threats. Another encouraging sign is that this week the Security Council imposed a travel ban and assets freeze on two government militia commanders and two rebels accused of abuses in Darfur. China and Russia abstained.

At last, there are signs of movement. Our own government must seize the initiative and do everything in its power to ensure UN troops are deployed to the region as soon as possible.