The Office for Government Policy Coordination has sought a further investigation into dereliction of duty by 12 officials at the state's administrative construction agency and the provincial government with jurisdiction over the site of a deadly underpass flooding in Cheongju.

The office, which is conducting a probe into the tragedy, said on Monday that officials at the North Chungcheong provincial government and its road management office appear to have failed to take preventive steps despite receiving multiple emergency calls prior to the flooding.

The construction agency is accused of insufficiently managing the ongoing construction of a temporary embankment along the nearby Miho River, which has largely been blamed for causing the river to overflow when the banks collapsed following heavy rainfall.

The office earlier sought a prosecutorial probe against six police officers for their alleged mishandling of the flooding.