All surviving crew members of a sunken South Korean ferry were in custody and under arrest, prosecutors said, as bad weather prevented the recovery of any of the more-than 100 bodies still missing.

The Sewol's captain, Lee Joon-Seok, and 10 crew members had already been arrested on charges ranging from criminal negligence to abandoning passengers.

The remaining four were arrested late on Saturday after warrants were issued, prosecutors said.

The confirmed death toll from the tragedy stood on Saturday at 187, with 115 unaccounted for - many bodies are believed trapped in the ferry that capsized on April 16 on a routine voyage to the southern resort island of Jeju with 476 people on board.

The ship's captain has been sharply criticised for delaying the evacuation order until the ferry was listing so badly that escape was almost impossible.

Prosecutors have raided a host of businesses affiliated with the ferry operator, the Chonghaejin Marine Company, as part of an overall probe into corrupt management.

The widening investigation has also seen travel bans put on eight current and former executives of the Korea Register of Shipping - the body responsible for issuing marine safety certificates.

A looming storm and high tides put a temporary halt to operations to recover the remains of those still missing over a week after the disaster.

Difficult conditions

Despite the difficult conditions, divers made several attempts to get into the ship, but to no avail.

"Divers could not go deep into the ship due to strong currents today," a rescue team official told AFP news agency.

Making up the bulk of the passengers on the 6,825 tonne Sewol when it sank were 325 high school students - around 250 of whom are either confirmed or presumed dead.

Although all hope of finding survivors has been extinguished, there is still anger and deep frustration among relatives of the missing over the pace of the recovery operation.

Around a quarter of the dead recovered so far have been found in waters outside the sunken vessel, and there are fears that some of the missing may have drifted free from the wreck.

"As efforts to find the missing people are becoming protracted, there are growing concerns among their families that bodies might be lost for good," a coastguard official said.

Authorities - wary of the palpable anger among relatives - have mobilised trawlers and installed 13-kilometre-long nets anchored to the seabed across the Maenggol sea channel to prevent the dead being swept into the open ocean.

Dozens of other vessels and helicopters have been scouring the site and beyond, with the search operation expanded up to 60 kilometres from the scene of the disaster.

Source: AFP