North Korea has thrown next month's unprecedented summit between Kim Jong-un and US President Donald Trump into doubt, threatening weeks of diplomatic progress by saying it may reconsider if Washington insists on unilateral denuclearisation.
The North's official KCNA news agency said on Wednesday Pyongyang had called off high-level talks with Seoul in the first sign of trouble in what had been warming ties.
Citing first vice minister of foreign affairs Kim Kye Gwan, KCNA also said the fate of the US-North Korea summit, as well as bilateral relations, "would be clear" if Washington spoke of a "Libya-style" denuclearisation for the North.
"If the US is trying to drive us into a corner to force our unilateral nuclear abandonment, we will no longer be interested in such dialogue and cannot but reconsider our proceeding to the DPRK-US summit," Kim Kye Gwan said, referring to the North's official name, the Democratic People's Republic of Korea.
North Korea had announced it would publicly shut its nuclear test site next week. Trump and Kim are scheduled to meet in Singapore on June 12.
US Secretary of State Mike Pompeo said on Sunday the United States would agree to lift sanctions on North Korea if it agreed to completely dismantle its nuclear weapons programme.
However, Kim Kye Gwan's statement appeared to reject such an arrangement, saying North Korea would never give up its nuclear programme in exchange for economic trade with the United States.
Kim Kye Gwan's statement came only hours after North Korea denounced US-South Korean military exercises as a provocation and pulled out of high-level talks with the South scheduled for Wednesday.
Any cancellation of the June 12 summit in Singapore, the first meeting between a serving US president and a North Korean leader, would deal a major blow to what would be the biggest diplomatic achievement of Trump's presidency.
Trump raised expectations for a successful meeting even as many analysts were sceptical about the chances of bridging the gap due to questions about North Korea's willingness to give up a nuclear arsenal that it says can hit the United States.
The doubt thrown over the Kim-Trump summit comes a week after Trump abandoned the 2015 nuclear deal between Iran and six world powers, under which Tehran curbed its nuclear programme in exchange for the lifting of most international sanctions.