It is the sixth case to come before the tribunal, based in the Dutch city of The Hague, and the first in which sexual violence during interrogation is being prosecuted.

The defendant, Anto Furundzija, is charged with failing to prevent the torture of two women prisoners and the rape of one of them by a subordinate.

The offences are said to have taken place five years ago in the town of Vitez, west of Sarajevo.

Mr Furundzija, who is 28, was arrested by Nato troops in December.

Prosecutors say he was the local commander of a special forces group, known as the Jokers, which operated within the Bosnian Croat army.

Mr Furundzija is charged with being present during the questioning of two women in mid-May, 1993, at the Jokers' headquarters in Vitez.

Another member of the group is said to have raped one of the women and threatened her sexually with a knife. Both were badly beaten.

The charges say Mr Furundzija did nothing to stop or lessen the violence.

More trials scheduled

Two more trials are scheduled at the Tribunal later this year.

A BBC correspondent says that, with 27 convicted or suspected war criminals in custody, finding staff and space to process them continues to be a major problem.