The United Nations and UK have warned of possible war crimes prosecutions amid renewed violence in the troubled Sudanese region of Darfur.
Janjaweed militias are accused of widespread atrocities
In the latest incident, 34 people were reportedly killed by pro-government Arab militias at a refugee camp.
UN Secretary General Kofi Annan called for an end to attacks, and for those responsible to be brought to justice.
In London, minister Hilary Benn said the International Criminal Court (ICC) in The Hague was collecting evidence.
"The government of Sudan should be under no doubt whatsoever," the international development secretary told the BBC.
"Those who are committing these crimes will in the end be brought to account and the government of Sudan is under an international obligation now to co-operate."
The UN Security Council has ruled that human rights violations in Darfur can be prosecuted by the ICC.
On Friday, the UN refugee agency said the death toll from Wednesday's attack on Aro Sharow camp in Western Darfur had risen to 34.
The attackers are believed to be Janjaweed Arab militiamen. It is thought to be the first direct assault on a refugee camp since the conflict began more than two years ago.
The Sudanese government denies any links to the Janjaweed and described them as criminals.
Mr Annan condemned "the attacks of civilians, humanitarian workers and assets and the African Union mission in Sudan".
About 5,600 peacekeepers from the African Union (AU) are monitoring an uneasy ceasefire in Darfur.
UN envoy to Sudan Jan Pronk on Friday said: "The names of the individuals responsible for the attack, when known, will be reported to the Security Council... as well as to the prosecutor of the International Criminal Court."
More than two million people have been forced from their homes and at least 180,000 have died in the conflict between the government and Darfur rebels.
The conflict began in early 2003, after a rebel group began attacking government targets, claiming that the region was being neglected by Khartoum.