A memorial ceremony was held Saturday to mark the 50th anniversary of the country's worst mine accident in the postwar era.

An explosion at the Mitsui Miike coal mine in Omuta, Fukuoka Prefecture, which used to be one of the country's largest, killed 458 workers. Another 839 suffered carbon monoxide poisoning.

The municipal government of Omuta was represented at the ceremony, becoming the first government body to be involved.

The mine, which closed in 1997, was operated by Mitsui Mining Co. The firm renamed itself Nippon Coke & Engineering Co. in April 2009.

Part of the coal mine's ruins are among the so-called Sites of Japan's Meiji Industrial Revolution that the government decided to recommend for inclusion on UNESCO's list of World Heritage cultural sites in 2015. The facilities, in eight prefectures, represent Japan's industrialization from the late 19th to early 20th centuries.