North Korean Kim Jong Un likely to launch ICBM on Sept. 9: Seoul PM

South Korea Prime Minister Lee Nak-yon has said that North Korean leader Kim Jong Un is likely to "launch another Intercontinental Ballistic Missile (ICBM) on September 9."

"The situation is very grave. It doesn't seem much time is left before North Korea achieves its complete nuclear armament," the prime minister told a meeting of defence ministers in Seoul on Thursday.

"A special measure is urgently needed to stop their recklessness," he added.

In another development, dozens were injured when protests broke out in Seoul over U.S. military adding more launchers to the high-tech missile-defence system THAAD in a southern town to counter North Korean threats.

Protesters tried to block the road where U.S. Forces were transporting four additional THAAD missile interceptor launchers to a base in Seongju and in the process entered into a scuffle with armoured riot police and that left many injured, CNN reported.

That rollout was "temporarily" completed on Thursday, a spokesman for South Korea's defence ministry said, adding it was necessary to counter increased threats from North Korea.

South Korea President Moon Jae-in held discussions on North Korea with Japanese Prime Minister Shinzo Abe on the sidelines of the Eastern Economic Forum in Vladivostok, hosted by Russian President Vladimir Putin.

After the meeting, Abe and Moon issued a statement saying "now is the time to further increase sanctions and pressures against the North as much as possible rather than seeking dialogue," according to Moon's spokesman Yoon Young-chan.