North Korea executed its nuclear envoy to the United States as part of a purge of officials who steered negotiations for the failed Hanoi summit between leader Kim Jong Un and U.S. President Donald Trump, a South Korean newspaper said on Friday.

Kim Hyok Chol was executed in March at Mirim Airport in Pyongyang, along with four Foreign Ministry executives after they were charged with spying for the United States, the Chosun Ilbo reported, citing a source with knowledge of the situation.

"He was accused of spying for the United States for poorly reporting on the negotiations without properly grasping U.S. intentions," the source said.