The ICBM launch is one of nearly a dozen weapons tests conducted by North Korea so far this year and marks the end of a self-imposed moratorium on long-range and nuclear testing.

It was a "breach of the suspension of intercontinental ballistic missile launches promised by Chairman Kim Jong Un to the international community," Moon said in a statement.

"It poses a serious threat to the Korean peninsula, the region and the international community," he said, adding that it was a "clear violation" of UN Security Council resolutions.

Pyongyang had officially paused long-range testing while leader Kim Jong Un embarked on high-profile negotiations with then-US president Donald Trump. But talks collapsed in 2019 and have been stalled ever since.

Despite biting international sanctions, North Korea has doubled-down on Kim's drive to modernise the military, and last week test-fired what analysts said was likely a "monster missile" -- a new long-range ICBM. It exploded soon after launch.

The US and South Korea had warned earlier this month that Pyongyang was preparing to launch an ICBM at full range.