Kim Yo-jong / Yonhap

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.