TOKYO (AFP) - Dozens of people from a Japanese coastal city took part in the country's first evacuation drill of a missile attack Friday (March 17), as regional tensions soar over accelerating North Korean threats.

The exercise in the city of Oga came less than two weeks after three North Korean missiles landed in the Sea of Japan (East Sea) off the northern municipality.

Japan has been on edge over North Korean launches since a mid-range ballistic missile flew without warning over the northern part of the country and into the western Pacific in 1998.

The pace of the North's missile development has intensified and its projectiles have since last year been landing ever loser to Japan's coast.

A total of 110 residents, including primary school students, participated in the drill, an Oga city official said.

"A missile appears to have been launched; there is a possibility that part of the missile will come down; it fell in the Sea of Japan," read a series of mock alerts sent to officials in cities in Akita prefecture.

The drill did not specify North Korea by name, only referring to "country X".

But the exercise was held on the premise that a North Korean missile had landed in Japan's territorial waters, a Cabinet Secretariat official said.

The drill was planned last year and was not conducted as a result of the North Korean launches earlier this month, officials said.

Three of four missiles Pyongyang fired on March 6 came down in Japan's Exclusive Economic Zone (EEZ) - waters extending 200 nautical miles (370 kilometres) from its coast - off Oga.

Under international law, territorial waters extend up to 12 nautical miles (22 kilometres) from the coast of a landmass.