An international rights group says United Nations peacekeepers failed to stop Sudanese troops from driving more than 100,000 people from their homes in the country's southern border region last May.

Amnesty International says the U.N. troops took no meaningful action to prevent Sudanese forces and allied militia from attacking people's homes in the town of Abyei.

In a report Tuesday on the events of last May, the group said virtually the entire population of Abyei was forced to flee and anything of value in the town was looted.

The London-based group said Sudan's army blew up the bridge linking Abyei to South Sudan to prevent people from returning home and said U.N. peacekeepers did nothing to stop the action.

Amnesty said former U.N. peacekeepers told the group that a decision was made not to militarily engage with Sudanese troops because they were better equipped.

U.N. officials were not immediately available to comment on the report.

Amnesty said there is no clear picture of how many people died or were injured in Abyei last May, and it called on the U.N. to ensure there is a proper investigation.

Abyei is in Sudan's southern region next to the new country of South Sudan, which became independent in July.

There was to be a referendum on the future of Abyei, but it never happened because Sudan and South Sudan could not agree on who was qualified to vote.