By Alex Jensen

SEOUL

North Korea's ruling party mouthpiece accused the United States on Tuesday of being "extremely rude" by again raising concerns over Pyongyang's treatment of its citizens.

In response to U.S. State Department spokeswoman Heather Nauert stating this month that any North Korean human rights violators will be held responsible, a Rodong Sinmun newspaper commentary described the move as "unacceptable" and warned Washington to be more careful.

It is a rare recent example of open criticism of the U.S. by the North, as the two sides are set for their first ever leaders' summit next month following clear signs of rapprochement in 2018.

U.S. President Donald Trump is expected to clarify details of an April 27 inter-Korean denuclearization agreement when he meets the North's leader Kim Jong-un in Singapore on June 12.

There were positive signs last week when North Korea released three American detainees, but there are still global concerns about Pyongyang's years of alleged crimes against humanity, including the use of torture and brutal prison camps.

The United Nations' expert on the North's human rights, Tomas Ojea Quintana, welcomed the release of the American prisoners but insisted more must be done to challenge Pyongyang's regime.

"As peace talks progress, a comprehensive assessment of the overall penitentiary system in North Korea will become unavoidable," he said in a statement.

There was no mention of the subject when the Koreas recently held their first summit in over a decade.

But the neighbors are in line to continue their dialogue revival this Wednesday, according to Seoul's Unification Ministry Tuesday.

Delegations will meet this Wednesday at the inter-Korean border village of Panmunjom for the first time since April 27.

"Through the inter-Korean high-level talks, (we) will push to lay the groundwork for sustainable development and lasting peace by having in-depth discussions and faithfully implementing the Panmunjom Declaration (of April 27)," the South's ministry said in a press release carried by local news agency Yonhap.