North Korean leader's sister Kim Yo-Jong on Wednesday slammed South Korea's foreign minister over her recent remarks on Pyongyang's antivirus measures, saying that she will "pay dearly" for them and warning the already frozen inter-Korean relations could get worse.

Last week, South Korea's Foreign Minister Kang Kyung-wha told a forum in Bahrain that the North has been unresponsive to Seoul's calls for cross-border antivirus cooperation, adding that Pyongyang's claim that it has no coronavirus cases is hard to believe.

"It can be seen from the reckless remarks made by her without any consideration of the consequences that she is too eager to further chill the frozen relations between the north and south of Korea," Kim said in a statement carried by the official Korean Central News Agency (KCNA).

"We will never forget her words and she might have to pay dearly for it," she said.

North Korea has claimed to be coronavirus-free, but it has maintained a high level of alert and antivirus measures, including tightening its borders since early this year.

The North has also rejected any outside help, saying foreign aid could increase the risk of a coronavirus outbreak. Kim's statement appears to reflect the North's stance on pushing ahead with antivirus efforts on its own and rejecting outside assistance.

Last week, state media said that Pyongyang has been placed on the highest level of alert against the coronavirus, suspending the operation of public facilities, such as restaurants and public bathhouses, and restricting the movement of people in the capital.

Kim's statement coincided with US Deputy Secretary of State Stephen Biegun's trip to South Korea this week for talks on the bilateral alliance and the stalled denuclearization negotiations between Washington and Pyongyang.

Her criticism against Seoul comes nearly six months after she issued a harshly worded statement in June threatening to blow up the inter-Korean joint liaison office in anger over the sending of anti-Pyongyang leaflets by defectors in the South into the North.

Pyongyang appears to have toned down its criticism in the statement as it was not released in any other media outlets for the domestic audience, such as the Rodong Sinmun, the official newspaper of its ruling party. (Yonhap)