Citing 17 safety violations, the transport ministry on Thursday revoked the business license of the operator of a tour boat that sank off Hokkaido in April, an incident that left 14 people dead and 12 missing.

It marks the first time the ministry has revoked a business license ¡ª the toughest punishment under the marine transportation law ¡ª for a tour boat operator because of a maritime accident. Shiretoko Yuransen, based in the town of Shari, Hokkaido, will not be able to apply for a new license for another two years.

¡°At this point, the direct cause of the accident is unclear. But a variety of safety measures didn¡¯t function properly because of the violations, which led to broken safety protocols,¡± the Ministry of Land, Infrastructure, Transport and Tourism said in a statement.