The South Korean ferry captain responsible for last year's disaster that killed more than 300 people, mostly school children, was given an increased sentence of life in prison Tuesday by an appellate court that convicted him of homicide.

A district court in November had sentenced Lee Joon-seok to 36 years in prison for negligence and abandoning passengers in need but acquitted him of homicide. Victims' relatives criticized the verdict at the time, saying it was too lenient. Prosecutors earlier had demanded the death penalty for Lee.

Lee's sentence was increased because the Gwangju High Court additionally convicted him on the homicide charges while upholding most of other charges that led to his November conviction, according to a court statement.

The appellate court sentenced 14 other navigation crew members to 18 months to 12 years in prison, the court statement said. In November they had received sentences of five to 30 years in prison.

Court spokesman Jeon Ilho said both prosecutors and the crew members have one week to appeal the verdicts.

Most of the victims were teenagers traveling to a southern island for a school trip. A total of 295 bodies have been retrieved but nine others are missing.

Many student survivors have said they were repeatedly ordered over a loudspeaker to stay on the sinking ship and that they didn't remember there any evacuation orders made by crewmembers before they helped each other to flee the ship. Lee has said he issued an evacuation order.

A year after the April 2014 sinking, the South Korean government is still reeling from lingering public criticism of its handling of the incident, the country's deadliest maritime disaster in decades. Violence occurred during a Seoul rally led by relatives and their supporters earlier this month, leaving dozens of people injured.

Last week, South Korea formally announced it would salvage the ship from the ocean floor off the country's southwest coast. Relatives of the victims hope that might locate the missing, including four students, and help reveal more details about the sinking. Some experts are skeptical about those wishes and remain opposed to spending taxpayer's money to lift the civilian vessel.

Officials say the salvage job is estimated to cost $91 million to $137 million and take 12 to 18 months.

Authorities blame excessive cargo, improper storage, botched negligence and other negligence for the sinking, and have arrested about 140 people. Critics say higher-level officials haven't been accountable.