Indonesia has increased security near Freeport McMoRan Copper & Gold Inc's
An Australian technical expert working for Freeport was shot dead in his vehicle on the road leading to the mine on Saturday.
The next day, a guard employed at the Grasberg mine was killed and five policemen injured in another shoot-out on the same road. Two more policemen were shot and wounded on Wednesday.
Freeport said its operations had not been affected, but hundreds of Freeport Indonesia workers have now been told not to travel along the road up to the Grasberg mine, spokesman Mindo Pangaribuan said.
"Production is not disturbed, production is still running well," he added.
"Production forecast in 2009 is 1.3 billion pounds of copper and 2.2 million ounces of gold. The forecast output can still be achieved."
The Grasberg mine has the world's largest recoverable reserves of copper and the largest gold reserves. It accounts for nearly 40 percent of Freeport's total copper reserves of 93 billion pounds, according to Freeport's website.
Indonesian police and Australian Federal Police are investigating the recent attacks. An Indonesian police spokesman said on Sunday secessionists could be behind the shootings.
The police and military said they have stepped up security in Papua, the easternmost part of the sprawling Indonesian archipelago. The Grasberg mine is about 3,350 kilometres (2,080 miles) east of Indonesia's capital, Jakarta.
"After the incidents we have increased security, we added (security) posts along the route from Timika to Tembagapura (the Freeport area) and we are increasing our patrols. We also added more personnel," Bagus Ekodanto, Papua police chief, told Reuters.
But some activists said the attacks may be the result of increasing tensions between police and military in the area, particularly over the provision of security for Freeport's operations, considered lucrative work.
Freeport Indonesia's share of the costs for its internal civilian security department was about $22 million in 2008, according to a filing it made to the SEC.
"Freeport Indonesia's share of support costs for the government-provided security, currently involving approximately 1,850 Indonesian government security personnel located in the general area of our operations, was $8 million for 2008, $9 million for 2007, and $9 million for 2006," it said.
"This supplemental support consists of various infrastructure and other costs, such as food, housing, fuel, travel, vehicle repairs, allowances to cover incidental and administrative costs, and community assistance programmes conducted by the military and police."
Indonesia's low-paid military has kept a tight rein on Papua in the past, not just because of the insurgency, but also because of attractive business opportunities including smuggling and the provision of security services, rights groups and academics say.
"Let's refrain from speculating whether it's army-police rivalry. Your guess is as good as mine," Defence Minister Juwono Sudarsono told reporters on Wednesday, adding that the attacks could be due to migrant workers in the area.
While initial investigations had shown the use of military weapons in the attacks, Sudarsono said that "doesn't necessarily mean that it was military who were involved because these rifles and bullets can be gotten by anyone in Papua."