By Elias Biryabarema

KAMPALA (Reuters) - Amnesty International on Monday accused Uganda of carrying out extrajudicial executions as authorities in the east African country said 62 people had died in clashes between a tribal militia and security forces in a restive western region.

The fighting between royal guards of a tribal king, Charles Wesley Mumbere, and a combined army and police force occurred on Saturday and Sunday in Kasese, the biggest town in Uganda's Rwenzori region located near the border with the Democratic Republic of Congo.

A regional police spokesman, Mansur Suwed, told Reuters on Monday at least 46 members of the king's guards died in the fighting, which also left 16 police officers dead.

"In a shocking display of heavy-handedness, many people appear to have been summarily shot dead and their bodies dumped," Amnesty International said in a statement on Monday.

The security crackdown had shown "shocking examples of unlawful killings and a complete disregard for human rights during the arrests ... the government must ensure that police and soldiers observe restraint and desist from extrajudicial executions," the rights group added.

Paddy Ankunda, spokesman for Uganda's military, said he had no immediate comment on Amnesty's allegations.

"We're preparing a comprehensive government statement which will be issued tomorrow," he said.

Ugandan police were not able to be reached to comment on the allegations.

Earlier on Monday, police said they had taken control of Mumbere's palace after the fighting and seized a cache of machetes, spears and petrol bombs.

Security detained Mumbere on Sunday and accused his supporters of trying to create a new state in the area.

The Rwenzori area has been experiencing intermittent unrest since Uganda's disputed February presidential election, which the electoral body said was won by long-ruling President Yoweri Museveni.

Uganda's largest opposition party Forum for Democratic Change (FDC) got overwhelming support in the area.

There has been no statement from the king, a supporter of the opposition.

"The town is calm but we're still patrolling and monitoring. We have burnt down all the camps they (the guards) had established and also we've taken over the royal palace," Suwed told Reuters earlier on Monday.

Police, Suwed said, had also seized a rifle, a pistol, four walkie-talkies and knives from the fighters, and increased patrols in Kasese town.

Some opposition officials have said in the past the government was likely stoking the violence in the area to punish it for shunning the ruling party, a charge the government has denied.

An opposition legislator from the region, William Nzoghu denied the royal guards were armed and accused the government of using excessive force when storming the king's palace.

"It was madness. The action of government was real madness," he said.

(Reporting by Elias Biryabarema; Writing by George Obulutsa; Editing by Katharine Houreld and Toby Chopra)