Salvage operators were preparing to move South Korea's sunken Sewol ferry on to another vessel to transfer it to port Friday, nearly three years after it went down with the loss of more than 300 lives.

The top of the wreck had been raised to 13 metres above sea-level by late morning, the maritime ministry said in a statement, just high enough to fit it onto a semi-submersible standing by to take it to Mokpo on the mainland.

The rusted, silted hull stood high out of the water between two giant salvage barges, still on its side as it lay on the sea bed but with both the white superstructure and the blue bulbous bow exposed.

"Today is the last day of the neap tide and we must finish loading the Sewol to the submersible," Lee Cheol-jo, a ministry official in charge of the operation told reporters, referring to when tides are at their weakest.

The complex operation -- one of the largest raisings of an entire ship ever attempted -- comes as the third anniversary approaches of one of the country's worst-ever maritime disasters, which dealt a crushing blow to now-ousted president Park Geun-Hye.

Almost all the dead were schoolchildren and it is thought that nine bodies still unaccounted for may be trapped inside the sunken ship.

Raising the ferry intact has been a key demand of the victims' families, although workers had to remove a rear ramp that was obstructing their efforts.

- 'No words to describe' -

Several relatives watched the much-anticipated operation unfolding from a boat near the site.

"I had seen footage of the vessel from time to time, but there are no words to describe what I'm feeling to see it above water," said Jung Seong-Wook, a father who lost his son in the deadly accident.

"I cried. I could only think about my son," Jung told AFP after returning from an early morning boat trip to the site.

Jung is among a handful of bereaved family members who have kept watch at a camp on a hilltop on Donggeochado -- the nearest island to the wreck, just 1.5 kilometres (a mile) away.

Other bereaved family members gathered at Paengmok harbour, an hour away from the site, huddled in front of a small computer monitor for any updates to the salvage operation.

"From time to time when the news mentions a possible obstacle, my heart stops," said Yoo Young-Hwa, who lost her daughter on the Sewol.

About 450 workers are involved in the painstaking efforts to lift the ship, which has a displacement of 6,825 tonnes but is now estimated to weigh between 8,000-8,500 tonnes including the silt piled up inside.

The vessel was lying more than 40 metres (130 feet) below the waves off southwestern South Korea and the operation, originally scheduled for last year, had been pushed back several times because of adverse weather.

source: AFP