Updated

Dozens of human rights watchdogs and lawyers on Friday urged Uganda's government to allow an independent investigation into killings by security forces during violent clashes with a tribal kingdom last year that left over 100 dead.

The coalition of 40 groups wants an investigation with international expertise into the confrontations between Ugandan forces and people loyal to the Rwenzururu kingdom. Human Rights Watch has said over 155 people died, with at least 140 deaths blamed on security forces.

Uganda's government has said the Human Rights Watch account had "several inconsistencies" and denied allegations that children were killed. It put the overall death toll at 103.

The clashes followed tensions between longtime President Yoweri Museveni's government and the Rwenzururu king, Charles Wesley Mumbere. On Nov. 27, military and police used force to enter the king's palace in the border town of Kasese in western Uganda.

The region is a hotbed of opposition to Museveni, and people in Kasese complain of marginalization by the central government. Tribal monarchs in Uganda have only ceremonial powers but are influential among their subjects.

Mumbere, who has since been charged and exiled from Kasese, is accused of leading armed tribesmen who threatened state security. The government has arrested and charged scores with murder, treason and terrorism.

No member of the security forces has been charged.

"The Ugandan government took significant steps to charge almost 200 civilians for their alleged involvement in the violence in Kasese," said Maria Burnett of Human Rights Watch. "But six months after this unexplained and overwhelming use of lethal force by the police and military, the government has taken no steps at all to investigate their role."

The king's supporters, armed with tools like machetes, would not constitute an armed group under international humanitarian law, the rights group said.