By Staff, Agencies

North Korea should take "actual action" towards giving up its nuclear weapons to break the deadlock in talks with Washington, a top security adviser to the South Korean President said, suggesting Seoul's patience with Pyongyang may be wearing thin.

President Moon Jae-in was instrumental in brokering the negotiations between Pyongyang and Washington, seizing on the 2018 Winter Olympics in South Korea to catalyze a rapid diplomatic rapprochement after a year of missile tests, threats and tensions.

But the first summit between North Korean leader Kim Jong Un and US President Donald Trump in Singapore in June produced only a vague commitment to "work toward complete denuclearization of the Korean peninsula".

Their second meeting in Hanoi last month broke up without agreement, or even a joint statement, as the two failed to come to a deal over sanctions relief and denuclearization.

Since then, Pyongyang said it is considering suspending the talks and images have emerged of rebuilding works at the Sohae rocket launch facilities.

That triggered international alarm that North Korea might be preparing a long-range missile or space launch, which could put the whole negotiations process at risk -- Pyongyang has not carried one out for more than a year and Trump has repeatedly said its continued moratorium is crucial.

A launch of any kind by the North would be a "disaster", said Moon's special adviser on national security Moon Chung-in.

The "outcome will be catastrophic", he told AFP.