A senior North Korean official thought to have been purged appeared at a state event on Monday.
Kim Yong Chol was pictured sitting five seats away from Kim Jong Un during a musical performance by the wives of army officers.
South Korean media had reported last week he had been sentenced to hard labor and ideological re-education over the failed summit in Hanoi in February.
The nuclear summit between Donald Trump and Kim Jong Un was cut short without an agreement being reached. North Korea had pushed for a total lifting of sanctions in return for only partially stopping its nuclear programme.
Kim Yong Chol has been North Koreas top nuclear negotiator since Kim Jong Un entered nuclear talks with the US early last year. He traveled to Washington and met President Donald Trump twice before Kims two summits with Trump.
Chosun Ilbo, the newspaper which first reported the purge, also said that senior envoy Kim Hyok Chol, who was involved in pre-summit working-level talks with American officials, was executed with four other officials from the Norths Foreign Ministry for betraying Kim Jong Un after being won over by the United States.