Lee Joon-seok, captain of sunken ferry Sewol, arrives at a court in Gwangju June 10, 2014. [Photo/Agencies]

SEOUL — South Korea's top court on Thursday upheld a life sentence for the captain of a ferry that sank last year, killing more than 300 people, most of them teenagers on a school trip.

The Supreme Court upheld a lower court that sentenced Lee Joon-seok, 70, to life imprisonment for charges that included homicide, the court said in a statement. The court ruled that Lee committed homicide by "willful negligence," concluding he fled his ship without giving an evacuation order, although, as captain, he is required by law to take measures to save his passengers.

The court also upheld prison terms of 18 months to 12 years for 14 other crew members who faced similar charges of negligence and passenger abandonment, but weren't found guilty of homicide or avoided such charges because they were subject to Lee's orders.

A total of 304 people died when the ferry Sewol sank off South Korea's southwest coast in April 2014 in one of the country's deadliest maritime disasters. Most of the victims were from a single high school.

Lee and his crew members have been the targets of fierce public anger because they were among the first people rescued from the ship when it began badly listing.

Lee has said he issued an evacuation order, but many survivors have said they were repeatedly ordered over a loudspeaker to stay on the sinking ferry and didn't remember any evacuation orders before they escaped.

The court ruled there was stronger evidence showing that Lee did not issue an evacuation order, and that he abandoned his duties as captain.

Lee's failure to take measures to save his passengers made it impossible for many to escape, the court said, meaning it was as if he had drowned them himself.