PARIS — The International Criminal Court in The Hague said Tuesday that it found testimony against a former rebel leader “too contradictory and too hazy” to convict him of a gruesome 2003 attack on a village in the Democratic Republic of Congo in which some 200 people were hacked to death and female survivors were raped and held in camps as sex slaves.

The acquittal of the leader, Mathieu Ngudjolo, was only the second verdict issued by the court since it opened its doors a decade ago. It drew harsh criticism from rights groups, who faulted prosecutors for not assembling a stronger case.

The trial had been tightly focused on the events of Feb. 24, 2003, in the eastern Congolese village of Bogoro. Prosecutors said the attackers used machetes to preserve bullets and burned some civilians alive.

In their ruling, the judges said that they did not question that the villagers had suffered atrocities but that there was not enough evidence to convict Mr. Ngudjolo of murder, rape and using child soldiers.