SEOUL, March 5, 2009 (AFP) - North Korea said Thursday it could not ensure the safety of South Korean flights over the Sea of Japan because of an upcoming joint US-South Korean military exercise.

A statement on official media said that no one knows "what military conflicts will be touched off by the reckless war exercises."

The North "is, therefore, compelled to declare that security cannot be guaranteed for South Korean civil airplanes flying through the territorial air of our side and its vicinity, its territorial air and its vicinity above the East Sea of Korea (Sea of Japan), in particular, while the military exercises are under way."

The annual exercise starts next Monday and lasts for 12 days. The North has denounced it as a prelude to war, while the US-led United Nations Command says it is purely defensive.