SEOUL - South Korean President Park Geun-hye named on Thursday a former supreme court justice with a reputation for fighting corruption as prime minister to replace an incumbent who resigned over the government's slow response to last month's ferry disaster.

Park officially apologizes for ferry disaster

Ahn Dai-hee will be mandated to oversee the reform of government structures, Park's spokesman Min Kyung-wook said.

"We believe he is the person who will successfully restructure the country by pushing through reforms of bureaucracy and government and normalising what has been abnormal in our society," Min said.

Park also accepted the resignation of the director of the National Intelligence Service and the presidential Blue House chief secretary for national security, Min said.

Ten days after the ferry Sewol capsized and sank on April 16 on a routine journey, Prime Minister Chung Hong-won offered his resignation amid an outpouring of anger over the pace of the rescue operation. More than 300 passengers died, most of them schoolchildren.

Park said this week she would overhaul government structures and improve safety oversight to guard against any recurrence of preventible disasters. She announced the breakup of the coast guard for failing in its duties.

Ahn was a prosecutor before joining the bench in 2006 and won praise for investigating corruption by confidants of a former president and others in positions of power.

Authorities have offered a reward equivalent to nearly $50,000 for the capture of Yoo Byung-un, the head of the family that owns the operator of the ferry that sank.

Police fanning out across the country handed out leaflets with Yoo's photograph, which was also posted online. The manhunt has included a search of both Yoo's house and the rural compound of a church that he co-founded, but he has eluded capture after ignoring summonses to appear for questioning.

On Wednesday, prosecutors and police spent hours combing the commune, but failed to find the 73-year-old fugitive wanted on charges of embezzling funds from ferry operator Chonghaejin Marine. Investigators see the alleged diversion of funds as one of factors that led to the sinking and loss of life.

Of the 476 passengers and crew, 339 were children and teachers on a high school outing. Only 172 people were rescued and the remainder are all presumed to have drowned.

Prosecutors believe that Yoo and his elder son, Yoo Dae-kyun, slipped out of the compound and could be hiding at the residence of a church member.

Dae-kyun and Yoo's other son, Hyuck-ki, are majority owners of Chonghaejin Marine through an investment vehicle.

Authorities offered the equivalent of $30,000 as a reward for the son's arrest.