The Democratic People's Republic of Korea (DPRK) lashed out at the United States on Sunday for "shielding" South Korea's plot to force some missing DPRK fisherpeople to "defect," the official KCNA news agency reported.

A protest was lodged with the U.S. side by the head of Pyongyang's delegation to the senior colonel-level military talks between the DPRK and the U.S. militaries, said the report.

It amounted to "an inhumane criminal behavior" that the U.S. side backed the South Korean authorities in their plot to force some missing DPRK fisherpersons to "defect by all sorts of appeasement and deception after holding them in custody for nearly a month," the KCNA quoted the protest notice as saying.

Last month, the South Korean authorities detained 31 DPRK fisherpersons who the KCNA said "had been gone adrift to the south side due to rough waves early in February." The South Korean side said Thursday that four of the detained were not willing to return to the DPRK.

Commenting on the U.S. side's investigation of the issue, which supported the South Korean side's claim, the KCNA said that the U.S. forces in South Korea "faked up" the results which "have neither justification nor scientific accuracy."

If the United States "truly sets store by humanitarianism and wishes to see the inter-Korean relations improved," it should play a due role in making the South Korean authorities immediately send back all the detained fisherpersons, the DPRK side's protest notice said.

The DPRK Red Cross Society has also sent a message to its counterpart in South Korea, urging Seoul to return all the detained DPRK citizens.