North Korea has fired three ballistic missiles into the sea off its east coast, South Korea's Office of Joint Chiefs of Staff said in a statement this morning.

The missiles were fired from a western region south of the capital Pyongyang, the statement said.

No other details were immediately available.

The launches came hours after the leaders of South Korea and China, the North's main diplomatic ally, met on the sidelines of the G20 summit in Hangzhou, China.

North Korea has staged a number of missile tests this year, with the most recent on 24 August with a submarine-launched ballistic missile flying some 500km towards Japan.

That launch, which was widely-condemned, marked what weapons analysts described as a clear step forward for North Korea's nuclear strike ambitions.

The United States described the "reckless" missile tests as a threat to civil aviation and maritime commerce in the region.

Speaking at the G20 summit, a senior US administration official said North Korea's continued nuclear development threatens its partners in the region and said the US will raise it concerns at the summit.

The official said: "Our commitment to the defence of our allies in the face of these threats remains iron clad".