SEOUL, April 23 - South Korean prosecutors on Wednesday raided businesses affiliated with the operator of a capsized ferry as part of a widening investigation into a disaster that left more than 300 people missing or dead.

The raids focused on 10 affiliates and firms related to the Incheon-based Chonghaejin Marine Company which owned the 6,825-tonne Sewol that was carrying 476 people when it sank a week ago off the southwest coast.

The operation was part of a probe into "overall corruption in management", Kim Hoe-Jong, a prosecutor on the case, told AFP.

More than 70 executives and other people connected with Chonghaejin and its affiliates have been issued 30-day travel bans while they are investigated on possible charges ranging from criminal negligence to tax evasion and embezzlement.

"We will also make efforts to retrieve profits made out of criminal acts and track down hidden assets to support financial compensations for (potential) lawsuits by families of the victims and the missing," Kim said.

The confirmed death toll from the ferry disaster stood at 146 Wednesday, but 156 were still missing, their bodies believed trapped in the inverted, submerged ship that sank in circumstances that have yet to be fully explained.

Prosecutors have so far arrested seven crew members including the captain, Lee Joon-Seok, who face charges of criminal negligence and deserting passengers.

Two more crew were taken into police custody on Tuesday, but have yet to be formally charged.