SEOUL (AFP) - The last messages to a victim of South Korea's Sewol ferry disaster were revealed on Friday (May 26) after a mobile phone was recovered from the salvaged wreck, officials said.

The vessel took hours to sink off the country's south-west coast in April 2014, killing more than 300 people in one of the country's worst maritime disasters.

As it unfolded, passengers frantically exchanged messages with friends and relatives.

"Please make sure you keep in touch with me," read one message on the recovered device, according to investigators. "Coast guards just sent a patrol boat. Don't die. Stay alive."

Another asked: "Helicopter rescued you?"

The last message on the phone asked whether the person had been rescued, urging him to "use someone else's phone and contact me" if it wasn't working.

The user last checked the phone at 9.29am on April 16, 2014, a committee inquiring into the disaster said in a statement. It ceased to operate 32 minutes later.

It gave no details of the owner, but confirmed he or she had died.

The KT Tech device was among 83 mobile phones retrieved from the wreck since it was salvaged in March and taken to the port of Mokpo for investigations and to search for the remains of nine unaccounted-for victims.

Three of them have since then been identified through DNA tests of remains found in the ship or on the sea bed near the wreck site.

Among the phones, 15 have been handed to digital forensic experts to try to restore their data, with two successful restorations so far.

Most of the victims were Danwon High School students on an excursion, and the sinking and botched rescue efforts dealt a crushing blow to now-ousted president Park Geun Hye.

Investigations concluded that the disaster was the result of numerous human factors, including an illegal redesign, an overloaded cargo bay and inexperienced crew.