Gordon Brown and French President Nicolas Sarkozy have called for intense action to secure a ceasefire in Darfur.
African Union soldiers will have a peacekeeping role in Darfur
The prime minister and Mr Sarkozy wrote a joint article which appears in the Times and French newspaper Le Monde.
They commit "as leaders to redouble our efforts to make further progress" in the war-torn region of Sudan.
A month ago the UN Security Council voted to send peacekeepers to the area where at least 200,000 people are thought to have died since 2003.
Mr Brown and Mr Sarkozy say the UN-African Union (AU) peacekeeping mission should be the starting point for efforts to bring peace to the region.
With more than two million people displaced and the fighting continuing, intense international action is needed to secure a ceasefire, they add.
Mr Brown has made Darfur a foreign policy priority, and the UN agreement authorising the deployment of up to 26,000 peacekeeping troops was the result of a joint British-French resolution.
The two leaders urge the government of Sudan and rebel leaders to engage fully in talks.
They warn they will work for further sanctions against those who continue to fight or obstruct efforts to find a political solution.
"The pain of the people of Darfur demands quick and decisive action from the international community", they write.
BBC political correspondent Carole Walker said the two leaders set out from their first meeting to make Darfur a priority.
The UN resolution will allow peacekeepers to use force to defend civilians and aid workers in Darfur from attack, with the first troops arriving in October.
AU chairman Alpha Oumar Konare has said enough African troops have been promised for the force that no resources from outside the continent will be needed.
The UN had expected to call on Asian troops, and there have been pledges of forces from Indonesia, Pakistan, Nepal and Bangladesh.
The mission, to be known as Unamid - the United Nations African Union Mission in Darfur - is expected to cost up to $2bn (£1.1bn) a year.