Militant groups in the Papua New Guinea province of Bougainville want to forcibly remove the six former Fiji soldiers in Tonu at the southern tip of Bougainville island.
The former soldiers are thought to be training security for pyramid scheme operator Noah Musingku.
The Autonomous Bougainville Government says it wants the Fijians out of the province by the 20th of this month when their visas expire.
Its spokesman, Peter Sawyer, says after this date they can not guarantee the safety of the Fijians.
He says groups such as the Me'ekamui faction don't want foreigners in the province establishing what appears to be a private army.
"For them to see some foreigners coming in and starting another army or helping to train what looks like an army to them is just not on. Most of them agree with the political leadership that Bougainville should be weapons free."
Mr Sawyer says a number of the militants and many other Bougainvilleans are owed money after paying into Noah Musingku's schemes for up to seven years.
The PNG Opposition leader, Peter O'Neill, says the PNG Government has to take a tougher stand on the presence of the former Fijian soldiers.
He says they have committed serious breaches against the National and Autonomous Bougainville Governments.
He says the province's constitution has a provision that specifically outlaws any kind of para-military training on the islands.
Mr O'Neill says both Governments have a responsibility to ensure that the laws of the country are not flouted.
