The Asahi Shimbun newspaper said it received an anonymous letter on Wednesday with a threat to bring down a local broadcast tower unless the media stops reporting about the Pana Wave Laboratory group.
The Asahi said the letter, delivered to the newspaper's Takamatsu bureau Wednesday morning, contained a metal nut the letter said was removed from a broadcast tower on Mt Aomine in Takamatsu, Kagawa prefecture in an area known as Goshikidai. The police later said 10 bolts were found removed from a 30-meter-high steel tower Kagawa authorities use for broadcasting emergency notices.