Five people were found dead in the Porgera gold mine in Papua New Guinea's Enga Province last Saturday after a routine underground blast.
The mine operator, Barrick Niugini Ltd, says in a statement that after a scheduled blast an injured man alerted staff that other trespassers who had been with him in the underground mine complex were missing.
The company says a search and rescue operation led to the discovery of five bodies.
The executive general manager of the company, Greg Walker, says it tragically demonstrates that the mine is not a safe place for unauthorised people to be.
Enga police say two of the deceased are from Laiagam and one is from Porgera but the other two are yet to be identified.
The governor of Enga, Peter Ipatas, says while he extends his sympathies, the tragedy is a warning to everybody who wants to trespass at the mine and mine illegally.