Media organizations in Tokyo were mailed statements Thursday in which the ultra-leftist Chukaku-ha (Middle Core Faction) claimed it was responsible for two explosions Tuesday that gutted two buses and damaged another in Matsudo, Chiba Prefecture.

The buses were parked in a depot owned by Keisei Electric Railway and its affiliate, Narita Airport Transport Service. In the statements, Chukaku-ha said that Keisei disrupted the movement to oppose Narita airport by starting construction of an extension of the Shibaya Railway Line in the Narita area.

It also expressed its determination to stop the construction of a new runway at the airport. In Tuesday's explosions, lead cables and batteries were found near the rear tires of the gutted buses, indicating the fires were set off by timing devices.