At least 55 people have been killed in fierce fighting that erupted in western Uganda between security forces and a separatist militia linked to a tribal king, police said Sunday.

Police spokesman Andrew Felix Kaweesi said 14 police officers and 41 militants had died in the clashes in the town of Kasese on Saturday, when fighters linked to the royal guard of the Rwenzururu kingdom attacked patrolling security forces.

Uganda's deputy government spokesman Shaban Bantariza said the militia were fighting to form their own republic and "harbour intentions to break away from Uganda".

"These militiamen have set up camps in the Rwenzori mountains from where they train and come to attack government installations " Bantariza said.

The town of Kasese, home to the king, was under lockdown Saturday evening.

The conflict in the area bordering the Democratic Republic of Congo has a long history. The Rwenzururu Kingdom started out as a separatist movement of the same name when the mainly Bakonzo community declared its own kingdom in 1962 -- seeking to break free from the yoke of the dominant Toro Kingdom in the region.

The move led to years of bloodshed until a settlement was reached in 1982 in which the movement laid down arms in return for a degree of local autonomy.

President Yoweri Museveni officially recognised the kingdom in 2009. However unrest has continued to simmer in the complex ethnic and political conflict.

King Charles Wesley Mumbere -- who has had a tense relationship with Museveni -- has denied connections to the militia.

Between February and March this year, over 50 people were killed in clashes between the security and rebels, according to police figures.