North Korea test-fired what appeared to be a short-range missile into the sea off its east coast Monday in the latest of a series of missile and rocket tests, military officials said.

It was launched at 10:30 am (0130 GMT) from a site northeast of Pyongyang towards the Sea of Japan (East Sea) and flew about 220 kilometres (130 miles), the South's joint chiefs of staff said.

Details were not given, but a military official told AFP on condition of anonymity: "North Korea appeared to have test-fired a new tactical or short-range Scud missile."

The launch was made near Ryongnim, some 60 kilometres south of the border with China, he said, declining to confirm a Yonhap news agency report that North Korea has built an underground Scud missile base in the region.

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

Almost 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.

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