KANO (Nigeria) • A public inquiry has accused the Nigerian army of killing 347 Shi'ite Muslims and dumping them in a mass grave in the northern state of Kaduna late last year.

The report provided a chilling description of how unfortunate timing along a busy highway in Zaria city led to bloody battles that decimated the Shi'ite sect known as the Islamic Movement of Nigeria. One soldier was killed during the fighting.

Two days of violence began on Dec 12 when Shi'ite worshippers set up a roadblock to control traffic for a flag ceremony at their national headquarters, obstructing the convoy of Nigerian army chief of staff Lieutenant-General Tukur Yusuf Buratai.

The troops tried to get the sect to let them pass, but when they were denied permission, shot their way through the blockade, the inquiry determined.

Afterwards, some of the soldiers decided that the roadblock constituted an assassination attempt on the general. They also heard that members of the sect were regrouping, calling in members from surrounding towns to fight back.

Soldiers began a search for weapons caches they believed had been hidden in the city by the sect's members. Ultimately they found bows and arrows and a few hunting guns, the report said.

"The Nigerian Army used excessive force," said the 193-page report issued on Monday by a Nigerian judicial panel, set up by the Kaduna state government.

It also said members of the sect - which has a reputation for radicalising its members and engaging in "habitual acts of lawlessness" - should be held responsible and called for those responsible for the killings to be prosecuted.

AGENCE FRANCE-PRESSE, NEW YORK TIMES