JAKARTA (Reuters) - Indonesian authorities have detained another 11 people in Papua province after three policemen and a soldier died in clashes with protesters demanding closure of a giant U.S.-run mine, police said on Saturday.

Fifty-seven people had already been detained after Thursday’s violence in the provincial capital, Jayapura, on the northeastern shore of Papua, about 3,500 km (2,200 miles) from Jakarta.

The clashes sparked fears of more protests against U.S. firm Freeport-McMoran Cooper & Gold Inc, which runs the mine.

Tensions have been running high in the area in recent days and, on Friday, police fired shots into the air as they patrolled the city. Three people were hurt in the incident.

Last month mine operations were halted for four days before protesters, mostly illegal miners, left the site near the town of Timika, about 500 km (300 miles) southwest of Jayapura.

The mine has been operating normally this week.

"The number of people detained has increased from 57 to 68," Papua police spokesman Kartono Wangsadisastra said on Saturday.

"Our team is still searching for those responsible for the criminal activities ... We have found the perpetrators’ identities and formed an investigating team to hunt for them."

He said 10 people had been declared suspects, but gave no details.

President Susilo Bambang Yudhoyono has rejected demands for the immediate closure of the mining operation, the country’s largest taxpayer, but said he would assign ministers to examine social grievances related to the mine.

There have been sporadic protests, both in Papua and Jakarta, since the February shutdown. Issues range from illegal miners seeking access to the mine area to the demands for closure of the mine, believed to have the world’s third-largest copper reserves and one of the biggest gold deposits.

Illegal miners often enter mining areas in Indonesia, a sprawling archipelago with huge deposits of such metals as copper, gold and tin.

The Freeport operation has been a frequent source of controversy over its environmental impact, the share of revenue going to Papuans, and the legality of payments to Indonesian security forces who help guard the site.