Alarm at the UN over "savage" killings
Militia leaders behind a massacre in the Democratic Republic of Congo last week could face the new International Criminal Court.
A commitment that those responsible would not go unpunished came from the United Nations High Commissioner for Human Rights, Sergio Vieira de Mello.
Winesses told the UN that up to 1,000 people were killed in the massacre in the north-eastern Ituri region of the DR Congo - an area rife with political and tribal tension.
Mr Vieira de Mello said he was alarmed by the "savage" killing spree, spread over 15 villages in the region.
"The perpetrators of these atrocities will be placed under the spotlight and will be obliged to answer for their actions," he said.
The International Criminal Court is the first permanent international tribunal established to try cases of war crimes, crimes against humanity and genocide.
On Wednesday, South African President Thabo Mbeki is hosting a meeting of heads of government from the Great Lakes region in Cape Town, which is expected to focus on the situation in DR Congo.
Many families have lost someone in the war
The meeting is being attended by the Congolese president, as well as the leaders of Rwanda, Uganda and Tanzania.
South African Foreign Minister Aziz Pahad said the massacre in Ituri had given the meeting a sense of urgency.
Details of the latest massacre emerged as an aid agency, the International Rescue Committee (IRC), published its account of the full scale of the genocide in the DRC.
Africa's worst war
It said 3.3 million people had died as a result of the war, making it the "tragedy of modern times".
The IRC said only 10% of the victims died violently, the rest dying from starvation and disease due to the activities of the various armed groups.
"This is really hell. We are not secure, even here. Anything could happen
Emmanuel Ralonji in Bunia
"This is a humanitarian catastrophe of horrid and shocking proportions... Yet, the crisis has received scant attention from international donors and the media," said the IRC president, George Rupp.
Africa's worst ever war began following the invasion of the north and east of the country by Rwanda and Uganda, to, as they said, prevent armed groups attacking them from Congo's territory.
This brought in armies, which have now left, from other countries to fight on the side of the Congolese Government.
However, clashes in the troubled north-eastern region, close to the Ugandan border, remain a potential stumbling block to peace.
Fearful of reprisals
The massacre in Ituri occurred last Thursday, a day after a peace agreement was signed in South Africa marking the end of 19 months of talks between the government, opposition parties, civil groups, militia and rebels.
On Monday, a Ugandan army spokesman denied any involvement in the massacre, saying his troops had been at least 15 km away.
President Joseph Kabila was sworn-in as a transitional head of state for the DR Congo this week for a period of two years before elections.
A new transitional government should be formed soon, including representatives of rebel groups who control the east of the country but they were not present at the ceremony in the capital, Kinshasa.
On Tuesday, villagers in Ituri were reported as saying they were fearful of reprisal attacks.
"This is really hell. We are not secure, even here. Anything could happen," Emmanuel Ralonji said in Bunia, not far from the scene of the massacres.