South Korea finds it "disappointing and regrettable" that its eight journalists invited to attend this week's dismantling of North Korea's nuclear test site are not being allowed to attend after all, according to a statement from Seoul's Unification Minister Cho Myoung-gyon Tuesday.

A group of foreign journalists excluding those from the South headed for the North via a chartered flight from China earlier in the day.

As announced amid unusually warm inter-Korean relations last month, Pyongyang is set to dismantle its Punggye-ri site -- where it has carried out all six of its nuke tests to date --between Wednesday and Friday, depending on the weather.

"We think it is disappointing and regrettable that [the South Korean] journalists cannot visit the North due to no follow-up measures after the North's invitation," Cho said in a message carried by local news agency Yonhap.

Inter-Korean travel is strictly restricted by both Seoul and Pyongyang, and the South has failed to confirm the trip by its journalists after North Korea abruptly canceled high-level bilateral talks last week, blaming military drills on the peninsula involving the U.S.

Another Unification Ministry official explained that Seoul tried again Tuesday morning to convey its travel list, "but the North declined to accept it".

"In spite of that, we take note of the fact that the North is pushing for the dismantling as promised and hope that it will lead to a successful summit between the North and the U.S.," Cho added.

Despite doubts about whether American President Donald Trump will even meet his North Korean counterpart as scheduled on June 12 in Singapore, South Korea's security chief Chung Eui-yong insisted in the U.S. Monday that the summit will go ahead.

Speaking aboard Air Force One on his way to Washington ahead of Tuesday's talks between Trump and visiting South Korean President Moon Jae-in, Chung denied a New York Times article claiming the American leader is having second thoughts about meeting Kim.

"During phone calls between our two leaders or talks between our National Security Councils, I never got such an impression," Chung said in comments reported by Yonhap.