Tony Blair has hinted that sanctions could be imposed against the Sudanese government if progress to resolve the situation in Darfur is not made.
The prime minister's comments come prior to tomorrow's International Human Rights Day, which is set to focus on the humanitarian crisis in Sudan.
Around two million people have been displaced by the conflict in the east African country's western region, where 400,000 people are believed to have died in the conflict during the last four years.
Earlier this year the UN passed a resolution for 20,000 troops to be sent to Darfur to replace the 7,000 African Union troops who have struggled to maintain order in the unstable region. If the peacekeepers struggle to find co-operation from Khartoum, Mr Blair said the international community could begin to explore other options to end the suffering.
"If rapid progress is not made, we will need to consider alternative approaches with international partners," Mr Blair warned.
"Both the government and the rebel movements should be clear that they will be judged on the basis of actions, not just words. They must move forward quickly to implement an immediate and strengthened ceasefire, commit to a political process and agree an effective peacekeeping force for Darfur."
The prime minister's comments were rejected by Dr James Smith, chief executive of the anti-genocide Aegis Group, who called for much greater international intervention into Darfur.
"Merely hinting at possible sanctions against Khartoum. shows that he still has no new plans for action, just more words," Dr Smith said.
"What's needed now goes well beyond mere sanctions against the architects of ethnic cleansing in Darfur, though it's a disgrace that only now are these being hinted at."