Incoming! Missile alert mistake

Civil servants in Japan had seconds to prepare for a nuclear missile attack - before a correction announcement revealed it was all a false alarm.

"This is information about a ballistic missile attack. This area is being targeted for attack," was the alert.

Red lights flashed as the message was mistakenly broadcast to 20 local government offices in Aichi prefecture, officials confirmed on Thursday.

North Korea fired ballistic missiles towards Japan in 1998 and 2006.

Safety alert systems were being tested at Nagoya City Hall, 170 miles (270 kilometres) west of Tokyo on Wednesday.

A staffer had left a volume switch turned on by accident, sending the alert throughout district offices.

Japan remains sensitive to the risk of attack from nuclear-armed North Korea and has been actively upgrading its missile defence systems.

"We were worried at first, but a correction was broadcast before we could panic," a disaster management official said.