"We believe they came through the windows and opening of the ferry's bow," Lee said, adding that DNA tests would need to be undertaken on the remains.

But on Tuesday night, the ministry told reporters that the bones had been confirmed as animal remains.

Kang Won-jin, a ministry spokesman, said officials who gave the earlier press conference assumed the bones belonged to a human at the time.

He said: "It wouldn't have been easy for those who were at the site to tell whether they belonged to the bones of a human or an animal."

Salvage operation

Officials said the vessel, currently attached to two salvage ships near where it sank, will be returned to Shin Port around April 4, depending on weather conditions.

Emotions were raw last week as the families of victims witnessed the ferry return to the surface. Some have criticized the recovery efforts, saying it had taken too long to happen.

"It's the first time in three years I've seen the ferry with my naked eye, and it's hard to understand why we couldn't lift it before," Jang Dong-won told CNN.

"The priority is to find the missing bodies and do the least damage to the ship so we can find the truth and the reason it sank."

For many of the families of the victims, the wait for answers has been agonizing.

"My son was the 220th body to be found, after 16 days," said Shin Chang-sik. "I can't imagine how the children were shouting and calling for their mother and father on the ship, I feel sorry for him and at the same time I am sorry (I couldn't be there)."

Shin said the disaster "feels like yesterday."

"My days stopped on April 16, 2014. I would do anything to turn the clock back to April 15th," he said.