North Korean leader Kim Jong Un has supervised a fresh test of a "super-large multiple rocket launcher" system, state media said on Wednesday - the latest in a series of provocations by Pyongyang.

South Korea's military said on Tuesday that the North had launched "unidentified projectiles" from the Kaechon area in South Pyongan province. They flew approximately 330km.

The launch came shortly after Pyongyang said it was willing to hold working-level talks on denuclearisation later this month with the United States.

Kim "gave field guidance" for Tuesday's test, the Korean Central News Agency reported.

The "super-large multiple rocket launcher" was tested in an exercise observed by Kim about two weeks ago.

The KCNA report said the test was aimed at "measuring the time of combat deployment" and implied another test could follow.

"What remains to be done is running fire test which is most vivid character in terms of the power of multiple rocket launcher," KCNA said.

On Monday, the North's vice foreign minister Choe Son Hui said in a statement carried by KCNA that the country had "willingness to sit with the US side for comprehensive discussions of the issues we have so far taken up" later this month, at a time and place to be determined.

Kim and US President Donald Trump adopted a vaguely-worded statement on the "complete denuclearisation of the Korean peninsula" at their first summit in Singapore in June last year, but little progress has since been made on dismantling Pyongyang's nuclear programme.

Trump and Kim had agreed to restart working-level talks during a meeting at the Demilitarised Zone dividing the Korean peninsula in June, but those talks have yet to begin.