The survivor was found floating in Lake Toba, the world’s largest volcanic lake, by a navy search team on Tuesday, rescue officer Captain Sigit Darsono told TVOne broadcaster.

“When we plucked him he said he was from the helicopter” before falling unconscious, Sigit said.

Earlier rescuers found a seat believed to be from the missing helicopter.

The helicopter, owned by the charter company Penerbangan Angkasa Semesta, disappeared on Sunday, the latest of a series of air accidents in Indonesia in recent months.

It was on a 45-minute trip to the Kuala Namu international airport in Medan city.

All five people on board were employees of the charter company.

Lake Toba is a 100km-long natural body of water occupying the caldera of a supervolcano.