Solomon Islands police say members of the so called Neutral Force will be arrested if it does not disband.
The assistant police commissioner John Homelo says the Neutral Force, made up mostly of ex-militants, has been guarding some Government ministries, particularly the Ministry of Reconciliation, Unity and Peace which handled compensation claims from the victims of the ethnic unrest.
Mr Homelo says police had thought the group had gone out of existence, but he says last week they became aware it had demanded further payment of tens of thousands of US dollars for its services.
He says it has been made clear to the group that police handle security in the country.
"We passed a message to our boys - if they heard anything about it, that it still exists, and then we'll deal with them.....arrest them, and take them before the court for illegally setting up that group."
The Prime Minister has said he does not know anything about the group, but the Opposition leader, Patteson Oti, says the government needs to explain if public funds have been used to pay it.