The construction cost of the gymnasium that collapsed in Gyeongju turned out higher than the initial estimate, authorities said on Tuesday, with the probe underway to identify whether the lethal accident was a result of shoddy construction.

The police said on Tuesday that the total construction cost for Mauna Ocean Resort in Gyeongju, a city 370 kilometers southeast of Seoul, stood at around 400 million won ($374,000), which is higher than the 150 million won reported by local media in the immediate aftermath of the disaster.

The initial estimate of 150 million won for the construction of the building that collapsed, killing 10 and injuring more than 100, drew negative responses from media outlets, some of which raised the possibility of substandard construction.

The police said it will investigate further into whether the 400 million won budget was enough to meet standards.

Aside from the construction cost issue, other evidence that might help explain why the building collapsed is being uncovered as police officers and professionals in engineering and safety conduct the investigation.

The team has so far discovered missing or broken bolts in pillars after studying the blueprint of the building, but they said the exact cause is yet to be determined.

The collapse was initially believed to be caused by the heavy weight of snow that had piled on top of the gymnasium roof.

The student council of Busan University of Foreign Studies was hosting a welcome event for its incoming freshmen, when the ceiling of the prefab building collapsed last Monday.

By Suh Ye-seul (sys@heraldcorp.com)