A day before a high-profile visit by Chinese President Xi Jinping, North Korea said it will not back down from developing nuclear weapons.

"Our status as a nuclear power is absolutely non-negotiable," said Kim Jong Un's powerful sister, Kim Yo Jong, in comments published by the official newspaper of record Rodong Sinmun on Sunday.

She is considered a key player in the country's communications and foreign policy.

"The policy of continuously strengthening self-defensive nuclear war deterrence, as declared by the head of ​state, is an irreversible and final conclusion that must be executed unconditionally," she added.Kim Yo Jong routinely acts as a mouthpiece for the North Korean state on behalf of her brotherImage: Ahn Young-joon/AP Photo/picture alliance

Kim orders 'exponential' nuclear buildup