JAKARTA (REUTERS) - Indonesia's search-and-rescue team has located the sunken ferry in Sumatra's Lake Toba, an official said on Sunday (June 24), after the vessel sank in a bad weather nearly a week ago with almost 200 people onboard.

The hydrographic survey "identified" the ferry 450 metres deep in the water, not far from where it sank on Monday, said Mr Nanang Henky Suharto, an executive director at PT Mahakarya Geo Survey, a firm involved in the search.

"We have found the suspected position," Mr Nanang Henky said after the survey located a structure underwater similar to the build of the boat.

Mr Nanang Henky added that further investigation by deploying underwater drones will be required to confirm the findings.

"Due to the depth, divers cannot be deployed," he said.

Divers, going down a maximum 40 metres, could do little in the volcanic lake that has never been properly surveyed.

In 2014, an AirAsia flight carrying 162 people crashed in the Java Sea. But the plane was in water only about 50 metres deep and was found within days.

Three people have been confirmed dead and 18 people were rescued after the 15-tonne wooden boat went down in Indonesia's deadliest ferry disaster for nearly a decade.

Some 192 people are missing, most believed to be trapped inside the boat as it slipped beneath the waves.

An official with search-and-rescue agency (Basarnas) said raising the ship would be required to recover the bodies.