Doug Stanglin

USA TODAY

Hundreds of text messages allegedly sent by missing students aboard a sunken ferry to family members were faked, according to Korea's Cyber Terror Response Center, South Korean media report.

The South Kerry ferry sank on Wednesday off South Korea's southwest coast with 475 people aboard. Officials say 28 bodies have been found and 268 are still missing.

South Korean news outlets on Wednesday had released some of the purported conversations.

The texts, ostensibly sent from students still trapped in the submerged vessel, begged for help or offered parting words to loved ones.

The Yonhap News Agency and The Korea Heraldquote Korea's Cyber Terror Response Center at the National Police agency as saying on Thursday that they had checked cell phone use logs of the 271 missing and concluded that none of them had sent any text or made calls after the ferry sank.

They found that none of the phones had been used since noon on the day of the accident, the Herald reports.

"We've checked over 300 phones, since some people owned more than one phone," police said, according to the newspaper.

One of the fake messages was sent from a phone owned by a fifth grader in Gimpo, Gyeonggi Province, the Herald reports.

The CTRC said it has asked regional police offices to try to determine who composed the messages, the Yonhap News agency reports.

Police said those responsible face criminal charges, including defamation and obstruction of justice. Officials said the purported hoax hurts the families of those missing and causes confusion for search teams.

Officials drew a sharp distinction between texts sent while the ship was still partially afloat -- which are believed to be real -- and those allegedly sent after the ferry was completely underwater.

Among the earlier dramatic texts that are believed to be genuine, ABC News, citing Korean TV, reported one in which an 18-year-old student identified as Shin wrote: "Dad, don't worry. I've got a life vest on and we're huddled together."

Dad's reply: "I know the rescue is underway but make your way out if you can."

"Dad, I can't walk out," she replied. "The corridor is full of kids, and it's too tilted."

Some of the earlier texts, such as those by ABC, were also cited by USA TODAY and other news outlets.