JAKARTA (AFP)--"Foreign countries" could be behind a series of deadly ambushes near a U.S.-owned goldmine in Indonesia's remote Papua province that have killed three people, the defense minister said Thursday.

The attacks by unidentified gunmen near Freeport McMoRan's massive Grasberg gold and copper mine could be an effort by foreign competitors to close the mine down, Juwono Sudarsono told reporters.

"What I think is don't let Freeport be closed, because it involves global competition over natural resources there are a number of countries that have an interest in destabilizing Freeport," Sudarsono said.

Sudarsono said foreign NGOs and governments had a history of backing groups that "agitate" in Papua, which has been the site of a low-level separatist conflict since the 1960s.

Asked which countries he was referring to, Sudarsono said: "Apparently many neighboring countries to the south."

Indonesia's southern neighbours are Australia and New Zealand.

Sudarsono said he saw no indication the attacks were the work of separatist rebels of the Free Papua Movement (OPM).

Freeport, whose Grasberg mine sits on the world's largest gold reserve, is the single biggest taxpayer to the Indonesian government.

Australian technician Drew Grant, 29, was shot dead Saturday when his car was attacked on the single road from the mountain-top mine, while a Freeport guard was killed in an ambush on the same road Sunday.

A third policeman who fled the Sunday ambush was found dead in a ravine the next day.

Five policemen were wounded Wednesday in a firefight on the road, which has been closed indefinitely to Freeport workers.

Military chief General Djoko Santoso has blamed separatist rebels for the attacks, but police have said there is no indication that is the case.

The apparent skill of the attackers, who used military-issue ammunition, and their ease in evading capture has fueled speculation by some analysts that security forces are using violence to extort more protection money out of Freeport.

Freeport says it paid more than a $1 million last year for police and military protection, but the military has recently denied receiving any such payments.