SEOUL (REUTERS) - North Korea lambasted South Korean President Moon Jae-in on Friday (July 20) for "needlessly kibitzing" about relations between Pyongyang and Washington and dismissed Mr Moon's pledge to take the driver's seat on the Korean peninsula as "sophistry".

North Korean state media, which has often derided the South and its former presidents as a "puppet" of US hostile forces, has notably refrained from criticising the Moon administration especially after this year's thaw in relations.

The Rodong Sinmun, North Korea's official party newspaper, slammed Seoul's recent praise of its own efforts to bring about the first inter-Korean summit in more than a decade in April, and an unprecedented summit between North Korea and the United States, under the liberal president's peace initiative.

"It's a self-exalting, farfetched allusion and vain kibitzing without realising their own circumstances," the Rodong Sinmun said in a commentary.

The newspaper did not mention Mr Moon by name but pointed to his remarks during a visit to Singapore last week that North Korea and the United States would face the "stern judgement" of the international community if their leaders fail to keep the promise they publicly made.

North Korean leader Kim Jong Un and US President Donald Trump agreed to work towards denuclearisation at their summit in Singapore on June 12, but there has been no sign of concrete action.

Seoul's Unification Ministry said it has no comment on the North's denouncement.

Mr Moon's initiative to play a central role is "nonsensical sophistry", said the newspaper, accusing Seoul of caring only about the view of its "master" Washington and failing to take any practical steps to fundamentally improve inter-Korean relations.

"It's a known fact inside and outside that the South does not have the capability to resolve the peninsula affairs and elicit an agreement," the report said.

"When we and the United States are making efforts to implement the Singapore agreement, who would listen to such rude, atrocious sophistry with a presumptuous forecast lacking reality?"

Dr Shin Beom-chul, a senior fellow at the Asan Institute for Policy Studies in Seoul, said the latest criticism could be intended to weaken ties between the South and the United States, and strengthen the North's edge in cross-border relations.

"They are trying to tell the South not to rely on the alliance too much or they won't talk, which would make Moon's policy a failure, while seeking some leeway on sanctions," Dr Shin said.

In another attack against the Moon administration, Uriminzokkiri, a North Korean propaganda website, urged it to repatriate a dozen North Korean restaurant workers who came to the South in 2016.

The 12 had worked at a North Korean restaurant in China. Pyongyang claims they were abducted by South Korean authorities. The South has said the workers defected of their own free will.

Uriminzokkiri said there could be an "obstacle" in the planned reunion of families divided by the 1950-53 Korean War next month if the workers are not returned.

It lashed out at Unification Minister Cho Myoung-gyon by name, accusing him of "siding with" the former government which it said plotted the workers' defection.

A ministry spokesman refused to comment, but stressed that the family reunions were agreed by Mr Moon and Mr Kim during their first summit in April.