Seoul, Jun 13 (IANS): South Korea on Monday announced it has begun the difficult operation to salvage the Sewol ferry, which sank off the southwest coast of the country in April 2014.

It is believed that nine bodies, of the over 300 victims most of them school children who died in the tragic sinking, are still in the sunken ferry.

The Chinese consortium Shanghai Salvage on Sunday lifted the front of the ship, which lies 37 metres deep and upside down on the seabed, and began to install the platforms to raise it to the surface, a spokesman for the Ministry of Oceans and Fisheries told EFE news.

Once the platforms are placed under the ferry, which will take around three to four weeks and also requires partial lifting at the rear, a marine crane with 92 steel cables will be attached to the structure.

The Chinese consortium began first preparations in March to lift the 6,825-tonne vessel, so that the ferry remains intact and the nine bodies of those still missing could be recovered, if they are still inside.

The operation to lift the ferry is expected to cost some 85.1 billion won ($72 million).

The Sewol capsized on April 16, 2014 when it was carrying more than twice the allowable load and had failures in its structure, according to the official investigation. Serious failures were also experienced during the evacuation process of the ferry, preventing the rescue of dozens of passengers.

The wreck of the ferry is South Korea's worst human tragedy in decades which shocked the country and generated strong criticism of how the government handled the situation.