The leader of Fiji's main opposition party Sitiveni Rabuka says he was alarmed to see a high chief arrested by armed military and police.
The Fiji police have taken Ratu Epenisa Cakobau into custody amid a dispute over who should be installed as paramount chief the Vunivalu of Bau.
Images in local media showed Ratu Epenisa being escorted by uniformed men carrying guns.
Mr Rabuka called for calm and respect for traditional protocols.
There was no place for the military to police a peaceful family in a traditional setting, he said.
Fiji's police chief confirmed soldiers were part of the police operation.
Police Commissioner Sitiveni Qiliho said in a statement the military forces were there to provide armed protection in the event of any confrontation with traditionally armed warriors who had already arrived on the island.
Brigadier General Qiliho said the police maintained the lead role in the operation and a few armed soldiers were present for police protection as the Fiji Police Force was unarmed.
Martial arts-trained police were also deployed, he said.