UK mining company Monterrico Metals' Rio Blanco copper deposit in northern Peru was set on fire on 1 November by 20 gunmen, resulting in at least two fatalities.
The attackers entered the $1.5bn copper deposit and burned the workers’ camp and killed two guards. Seven other workers are still missing, Rio Blanco manager Wu Jian told Radio Programas.
"No one knows exactly what happened but the camp has been completely destroyed," Wu said.
"We only know that two of our workers are dead."
Since 2005 the mine has been attacked at least three times by protesters in opposition to alleged environmental contamination, according to Bloomberg.
The Rio Blanco deposit, which contains 1.26 billion tonnes of copper, has the capacity to annually generate 220,000t of copper.
Monterrico planned to commence production at Rio Blanco in 2011.