Rescue divers retrieved one more body early Sunday morning from a ferry that sank off South Korea's southwest coast last month, bringing the confirmed death toll to 286, officials said.

The body of a woman was recovered from the crew's cafeteria on the third-floor dock at around 5 a.m., the government emergency response team said.

The number of those still unaccounted for dropped to 18 as the search and rescue operation entered the 33rd day.

The 6,825-ton ferry Sewol carrying an estimated 476 passengers capsized and sank off the southwestern island of Jindo on April 16, with only 172 people rescued on the day of the sinking.

Of those on board, 326 were students from Danwon High School in Ansan, just south of Seoul, who were on a school trip to the southern resort island of Jeju.

The Navy, Coast Guard and civilian divers plan to resume their search for the remaining missing people at low tide later in the day, officials said.

Waves in the area were expected to reach around 0.5 meter on Saturday, with wind blowing at a speed of 3.5 meters per second, according to meteorological authorities.

The tragic disaster, one of the worst maritime accidents in South Korea, has dealt a serious blow to the administration of President Park Geun-hye over the botched initial response, lack of safety measures and cozy link between authorities and the ship's operator.

On Friday, Park made a direct apology to relatives of the victims as she struggled to contain the political fallout from the disaster ahead of the upcoming local election slated for early next month.

Late Saturday, 30,000 people, including some families of the ferry victims, joined what would become the biggest street demonstration over the ferry sinking, according to civic groups.

Police estimated the number of participants at around 10,000. (Yonhap)