Two security guards have been killed and two are missing after an armed attack on a Chinese-owned mine in northern Peru, authorities say.
Up to 20 men with guns attacked the Rio Blanco copper exploration project, according to mine manager Wu Jian.
He described the attack as "an act of terror" and said it may have been intended to scare off investment.
Correspondents say the attack took place at the scene of one of Peru's most bitter mining conflicts.
In 2005, police allegedly shot dead one protester and tortured about 30 others after local people marched against the mine's construction, saying it would pollute their water supply, the BBC's Dan Collyns in Lima reports.
The Rio Blanco mine, which is located in Piura department, 520 miles (840km) north of Lima, is run by the UK's Monterrico Metals company, a subsidiary of the Chinese Zijin Mining Group.
Monterrico Metals faces a British lawsuit over the torture allegations but denies any wrongdoing, our correspondent says.
Speaking to Canal N television on Monday, Mr Wu said the armed men had opened fire on guards at the mining camp on Sunday morning and had then set fire to the site.
"This is evidently an act of terror, of violence... and it would not surprise me if there are political and economic interests at play to scare investment away, to create an image of political instability," he said.
Peru's President Alan Garcia called for a full investigation into the attack and said the state "must act with much severity" against those responsible.
"There are many agitators, looking to sow acts of violence and slow some investment projects. This we already know," he said.
The local environmental group, which opposes the mining project, has denied any involvement, our correspondent says.
The government had hoped the controversial project would produce thousands of tonnes of copper, he adds, but it has sparked so much bloodshed and tension it may never get off the ground.