The office of President Moon Jae-in issued no immediate formal response Saturday to North Korea's statement mocking his efforts to facilitate nuclear talks between Pyongyang and Washington.

Kim Kye-gwan, formerly the North's top nuclear negotiator, took issue with Cheong Wa Dae's announcement Friday that it conveyed US President Donald Trump's congratulatory birthday message to North Korean leader Kim Jong-un.

Returning from a trip to Washington DC, Chung Eui-yong, director of Cheong Wa Dae's national security office, told reporters that Trump had asked Moon to deliver the message to Kim.

He said the South had conveyed it to the North, making headlines here. Moon has, meanwhile, declared plans to resume full-scale efforts for dialogue with the North and for resuming inter-Korean projects.

Kim, currently a foreign ministry adviser, effectively warned Moon not to meddle in North Korea-US relations any more.

He said the South's authorities had sent Trump's message "in an extremely urgent notice."

"But they seem not to know that there is a special liaison channel between the top leaders of the DPRK and the US," Kim said in an statement translated into English and carried by the Korean Central News Agency.

DPRK stands for the communist nation's official name, the Democratic People's Republic of Korea.

Kim added the North had earlier received the message from Trump on the occasion of the North Korean leader's Jan. 8 birthday.

He said the Moon administration "seems it still has lingering hope for playing the role of 'mediator' in the DPRK-US relations."

"It is somehow presumptuous for South Korea to meddle in the personal relations between Chairman of the State Affairs Commission Kim Jong-un and President Trump," he added.

His statement suggests Pyongyang is implementing its typical strategy of seeking to talk only with Washington, bypassing Seoul.

Cheong Wa Dae has not responded yet to it publicly and has been waiting for Pyongyang's response to Moon's overtures in his New Year's address.

Moon proposed the two Koreas jointly create the conditions for Kim Jong-un to make an agreed-upon visit to South Korea. He called for dialogue on various joint projects and exchanges including for upcoming sports events.

The North's foreign ministry adviser, however, made no mention of it in the statement.

He also left the door open for denuclearization talks with Washington. (Yonhap)