Indonesian troops in West Papua province have exchanged gunfire with an unidentified armed group close to where three people, including two American nationals, were killed on Saturday.

We have received information from local police sources that there are indications that the act was committed by elements of OPM (rebels)

Foreign Ministry spokesman Marty Natalegawa

The incident occurred about 0800 local time (2300 GMT Saturday), Papua Major General Simbolon Mahadin said.

Security officials said a soldier was injured in the clash.

Police and troops have launched a major operation to hunt down those behind Saturday's attack, in which nine other foreigners and five local people were also injured.

However the search was suspended after bad weather closed in on the area.

Separatist movement

No group has claimed responsibility for the attack - the worst incident involving foreigners ever to take place in West Papua.

However government officials said they suspected separatist rebel group the Free Papua Movement (OPM), Reuters news agency reported.

There has been a separatist movement in West Papua since the 1960s

"We have received information from local police sources that there are indications that the act was committed by elements of OPM," Indonesian Foreign Ministry spokesman Marty Natalegawa said.

There has been a separatist rebellion in the province - formerly known as Irian Jaya - since the 1960s, but this is the first time foreigners have been targeted.

The separatist rebellion in the province has been very low-key, with violent attacks by the rebels usually rare.

Both attacks took place very close to the American-owned Freeport mine, which is the world's largest gold mine and is protected by hundreds of Indonesian troops.

Freeport has been criticised by activists for its environmental record and its impact on the local community.

The company released a statement on Sunday saying that it "deplored" the attack but that operations were continuing as normal.

"Indonesian security officials... have provided assurances that the PT Freeport Indonesia mine facilities and surrounding communities are secure," it said.

Expatriate community

According to the police, in Saturday's attack five gunmen blocked off the road leading to the mine complex and stopped two vehicles which had been travelling along it, before opening fire.

The most seriously injured were flown for treatment either in Australia or in Jakarta.

Most are in a stable condition, but one woman is said to still be critically ill, the Associated Press news agency reported.

Most of the victims were teachers at the international school set up for Freeport employees.

There are approximately 1,000 expatriate workers at the mine - the majority are either American or Australian.