Japanese policemen cover with a blue sheet and inspect a small drone which was found on the roof of the Japanese PM's office (AFP)
Japan is launching an investigation into the landing of a drone on the roof of Prime Minister Shinzo Abe's office building, a government spokesman said, after media reported "minuscule" traces of radiation were found.
Japan Chief Cabinet Secretary Yoshihide Suga said police were investigating Wednesday's incident and that the government may consider new regulations on drones.
Police found the radiation to be low enough not to be harmful to humans, media said.
© Thomson Reuters 2015