Banjir Ambarita, Jayapura – Security officials at Freeport Indonesia's massive Grasberg Mine have detained nine foreign nationals who said they were mountain climbers, according to a source within the company.

The nine hikers allegedly entered the open pit mine in Papua province, which is the largest gold mine and the third largest copper mine in the world, at some point on Sunday and were detained by security later that day because they did not have a permit to enter the area.

The climbers have been identified by the anonymous source within the company as Swiss nationals Michel Wirth-Fragata, 44; Silvan Schenk, 57; Matthias Halchey, 34; Fritz Yacobv, 60; and Daniel Meyerhoff, 45; German national Reinhard Buscher, 61; Austrian national Alois Fuchs; and Matheus ven der Maulen, 59, from the Netherlands.

The ninth climber and the only female in the group, who has been identified only as Elen Anezlua, 42, was taken to the hospital in Tembagapura to receive treatment for severe dehydration.

The others were taken to the Freeport security office in Sugapa Grasberg. Local police were not immediately available to comment.

Freeport Indonesia, a subsidiary of US mining giant Freeport McMoRan, operates gold and copper mining in Papua's Timika district. The Indonesian government owns a stake in Freeport Indonesia as well.