A drone carrying small traces of a radioactive material landed on the roof of Japanese Prime Minister 's office in protest against the government 's nuclear energy plans . The police and bomb squad were called after the four-propeller , 50-centimeter wide drone , was spotted by member of the Prime Minister 's staff , on the roof of his principle office and residence in Chiyoda-ku , Tokyo . The drone was equipped with a small camera and a plastic bottle containing small traces of a radioactive material , according to Japanese media . Radioactive : The drone , which landed on the roof of the Japanese Prime Minister 's official residence , was found to contain traces of a radioactive substance . Alert : Police and security officers investigate an unidentified drone found on the rooftop of the Prime Minister 's official residence in Tokyo . The radioactive material is likely caesium , a soft metal and harmless to the human body , Tokyo Metropolitan Police said . It is not known who flew the drone onto the building but it is widely suspected it was someone protesting against the country 's nuclear policy . People in Japan have become increasingly wary about the number of nuclear power plants in the country , following the disaster at the Fukushima Daiichi nuclear power plant after the Tōhoku earthquake and tsunami in 2011 . Flown in : The blue tarpaulin covering the drone can be seen next to the helicopter pad on the roof of the Prime Minister 's office in Tokyo . Guarded : Police and the bomb squad were called in after a member of the Prime Minister 's staff noticed the drone on the roof . Tests to determine whether to plant should be decommissioned are currently being carried out , though many are skeptical over whether it would happen . Meanwhile , the Japanese government reportedly plans to dump 30 million tonnes of radioactive debris from the disaster in a waste complex by nearby village , Okuma . Anti-nuclear protests were held outside the Kagoshima District Court to stop reactors at Kyushu Electric Power Co 's Sendai nuclear-power station in Satsumasendai , southwest Japan from being restarted , amid fears they were at risk fro earthquakes and volcanic eruptions . Standing guard : A police officer outside Prime Minister Shinzo Abe 's official residence in Tokyo . Investigations : Officers comb the roof for clues after a drone ( pictured right ) landed on top of the Prime Minister 's official residence in Tokyo . Prime Minister Shinzo Abe was pushing for the reactors to be put back online as he wants to cut Japan 's dependence on imported fossils fuels . The courts agreed , meaning they will be back online in less than two years . The drone was initially covered with a piece of cardboard and covered by blue tarpaulin before being removed . Mr Abe was not in residence at the time as he is currently in Indonesia attending the Asia-Africa conference in Jakarta . Chief cabinet secretary Yoshihide Suga said police were investigating Wednesday 's incident and that the government may consider new regulations on drones .
Remote nuclear device had miniscule amounts of radioactive substance . Follows protests over plans to restart existing nuclear reactors . controversy over nuclear policy stems from nuclear disaster after 2005 . Prime Minister Shinzo Abe was not in residence at the site .