Updated

The parents of an Italian tourist who went missing while hiking one of Chile's most active volcanoes arrived in the South American country on Monday to join the search for him and two companions.

Luca Ogliengo's parents have rented a helicopter to assist rescuers.

Teams led by special police have been sweeping the area around the Villarica volcano in Chile's central valley since Thursday morning but have found no trace of Ogliengo, Dmitry Sivenkov of Russia and Gillhem Bellon of France.

The hikers haven't been heard from since Wednesday night, when one of them called his girlfriend, telling her it was getting dark and that they would sleep overnight at the volcano and descend the next day.

Authorities say they were unprepared to sleep on the volcano and that a cold front that night that brought snow, which may have covered their footprints.

The search began early Thursday after the snowy weather cleared out and rescuers continue to search the area on Tuesday afternoon.