North Korea has fired a short-range projectile towards the sea off its east coast in the latest of a series of missile and rocket tests, military officials from South Korea have said.

The projectile was launched on Monday at a site northeast of Pyongyang towards the Sea of Japan, a spokesman for the South's joint chiefs of staff said.

"The projectile flew about 220km, but we have no information yet on its type", he told AFP news agency.

Monday's exercise came as cross-border military tensions run high following a series of missile, rocket and artillery launches in July and August.

Three weeks ago, the North fired five short-range rockets into the sea just as Pope Francis arrived in Seoul for a five-day visit.

The North often fires missiles and rockets as a show of force or to express anger at perceived provocations, but the frequency of the recent tests is unusual.

UN resolutions bar North Korea from conducting any launches using ballistic missile technology.

However, the North has defended the missile launches as a legitimate exercise in self-defence and a response to US war manoeuvres.

Source: AFP