Life rafts and escape chutes on a sister ship to the sunken Sewol ferry have been found to not work properly, the Reuters news agency has reported investigators as saying.
More than 300 people, most of them students and teachers from the Danwon High School near Seoul, are dead or missing presumed dead after the April 16 disaster.
The confirmed death toll currently stands at 181.
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The largest advertising firm in the world and a global law company with offices in London were among the targets.
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