TOKYO: Improvised rocket launchers were fired close to a US airbase near Tokyo, police and the American military said Friday, with suspicions falling on one of Japan’s small ultra-leftist groups.

No-one was hurt and no damage was done in the incident, which media reported came just hours after the arrest of a senior member of a radical faction, and followed a pattern seen four years earlier.

“The incident occurred at 11:30 p.m. on Thursday. Flying objects were launched near the US military’s Yokota Airbase,” a spokesman for Tokyo Metropolitan Police said.

“Several reports were made by neighbors that they had heard explosions at about 11:30 pm. Police discovered two steel pipes, two wires, batteries, and so forth.

“No damage has been reported so far and police have not found the projectiles.”

Local media reported the pipes were buried in the ground, with the upper end pointing in the direction of Yokota Airbase.

A statement from the US military confirmed the presence of “an improvised mortar launch outside Yokota.”