Kim Yo-jong, the sister of North Korean leader Kim Jong-un, says North Korea will never back down on its status as a nuclear-armed state, warning that it will not tolerate any threats.
Chinese President Xi Jinping is set to visit North Korea on Monday for the first time in nearly seven years as Beijing looks to reinforce ties with Pyongyang, China's only formal treaty ally.
Xi will meet Kim Jong-un and exchange views on bilateral relations and issues of common concern, China's foreign ministry said.
Kim Yo-jong also called US claims that Xi and US President Donald Trump confirmed a goal to denuclearise during a May summit "false".
"We have the most accurate information" on whether the claims are true or not, she said, without elaborating.
Early this week, North Korea unveiled a new nuclear material production factory where Kim Jong-un called for an "exponential" expansion of the country's atomic arsenal.
Analysts said the new uranium-enrichment site appeared aimed at reinforcing North Korea's negotiating position ahead of the Xi-Kim summit while justifying an acceleration of its nuclear build-up.