An investigation has revealed that the officer responsible for navigation on a ferry that ran aground off the southwestern county of Sinan was distracted by a mobile phone at the time of the collision.

Authorities said Thursday that a preliminary inquiry confirmed that the ferry had struck an uninhabited islet while traveling on autopilot through a narrow strait.

The Queen Jenuvia 2, carrying 267 passengers and crew, ran aground at Jok Islet near Jangsan Island in Sinan at around 8:16 p.m. while en route from Jeju to Mokpo.

The investigation found that the officer had left the vessel on autopilot and was using the phone in an area that required manual navigation.

As a result, the ferry failed to change course when required and ran aground on Jok Islet, with roughly half of the hull ending up on land.

The Coast Guard said that given the evidence of occupational negligence, it plans to press criminal charges against those responsible.