The administrator of the Papua New Guinea island of Bougainville says he suspects an Australian plane flew in weapons to an area held by the rebel leader, Francis Ona.
Police have charged the plane's Australian owner and pilot for landing illegally two weeks ago, and are hunting for another Australian and a British man who are thought to have vanished in the jungle.
Peter Tsiamalili says people near the deserted mine at Panguna noticed new weapons in the area.
Mr Tsiamalili links the appearance of the arms to the plane.
He says it comes at a crucial time in the peace process.
"We are going through a major phase of weapon disposal, and that has gone very successful under the supervision of the UN, and we are trying to work towards concluding that exercise so we can move on to the next phase of preparation for elections for an autonomous government to be held early next year."
A PNG newspaper, The National, says the weapons have enabled Mr Ona to begin military training with a thousand men.