A suspected World War II bomb was found Thursday on the premises of Japan’s crippled Fukushima nuclear plant, an official said, with police called in to investigate.

The 85-centimeter┬álong object, believed to be an unexploded bomb dropped by the United States during the war, was discovered by workers constructing a parking lot close to the facility’s reactors, a spokesman for Fukushima operator Tokyo Electric Power Co (TEPCO) said.

TEPCO called police immediately upon finding the object, suspending construction work and roping off the area, which is around one kilometer from the reactors, he added.

There was no impact on ongoing decommissioning operations at the nuclear plant, which suffered meltdowns in March 2011 after a powerful earthquake spawned a huge tsunami.

Japan’s Jiji Press reported that under such circumstances, police call in bomb disposal experts from Japan’s military.