Prosecutors investigating April's deadly ferry sinking apologized Monday for so far failing to arrest the ferry operator's fugitive owner, vowing to apprehend him as quickly as possible.

   A massive manhunt has been under way for weeks for Yoo Byung-eun, who is wanted for a string of corruption charges and irregularities that are believed to have contributed to the April 16 sinking of the Sewol that claimed more than 300 lives.

   Police have previously combed through the city of Suncheon, 415 kilometers south of Seoul, and a religious retreat run by Yoo's religious sect in Gyeonggi Province attempting to arrest Yoo. But the 73-year-old fugitive has been one step ahead of the police search.

   "I am well aware of pubic concerns and criticism over the delay in efforts to take legal action against Yoo and his family, who contributed to the tragedy of the ferry Sewol," said Kim Hoe-jong, the head of the special investigation team at the Incheon District Prosecutors' Office. "As the head of the investigation, I feel very sorry."

   "The prosecution will make utmost efforts to arrest the Yoo family as soon as possible and to bring them to justice," Kim said.

   The prosecutor also warned against any attempts to help Yoo evade the dragnet, saying the prosecution will never tolerate such attempts and take punitive action on those who are caught helping the Yoo family.

   Prosecutors suspect that Yoo effectively owns Chonghaejin Marine Co., the ill-fated ferry's operator, through two of his sons and is responsible for the ship's allegedly lax safety practices.

Motivated by profit, the operator overloaded the ship with passengers and cargo even though its balance was substantially compromised after a remodeling.

   As part of its efforts to arrest the owner family, the prosecution last week hiked the amount of the rewards for information leading to the arrests of Yoo and his eldest son, Dae-kyun, to 500 million won (US$488,158) and 100 million won, respectively.

   Also on Monday, the prosecution added 10 more prosecutors and investigators to the special investigation team as they stepped up the manhunt for the Yoo family.

   The prosecution is reportedly planning to search the religious retreat in Gyeonggi Province again to investigate the possibility that Yoo's followers are helping the fugitives. There has even been speculation that Yoo or his son may have snuck back into the compound after the initial search failed to find them on the premises.

   "People guarding the compound have beefed up efforts to check and screen anyone entering the religious retreat," an investigator said.

   State prosecutors have also vowed to freeze Yoo's wealth.

   Earlier in the day, investigators raided Dae-kyun's home in Seoul and confiscated works of art. (Yonhap News)