SEOUL, June 3 (Reuters) - North Korean senior official and former top nuclear envoy Kim Yong Chol accompanied leader Kim Jong Un to a Sunday art performance, state media KCNA said on Monday, signaling that the former spymaster is alive and remains a force in North Korea's power structure.

South Korean newspaper Chosun Ilbo reported on Friday that Kim Yong Chol, Kim Jong Un's right-hand man and the counterpart to U.S. Secretary of State Mike Pompeo before the failed Hanoi summit, had been sent to a labor and re-education camp in Jagang Province near the Chinese border, citing an unidentified North Korea source.

Asked about the last U.S. contact with Kim Yong Chol and North Korea in general on Sunday, Pompeo declined to answer, saying: "We conduct our negotiations in private."

During an amateur art performance by the wives of officers in the North Korean Army attended by Kim Jong Un and his wife, Ri Sol Ju, on Sunday, Kim Yong Chol was among "leading officials" who accompanied them, according to KCNA on Monday.

He was the 10th official named among 12 mentioned overall.

As Kim Jong Un's point man for nuclear talks with the United States, Kim Yong Chol was apparently censured for the summit's collapse by being removed from a key party post, a South Korean lawmaker said in April.

Kim Yong Chol was pictured standing behind Kim Jong Un in an official photo released from a session of North Korea's rubber-stamp legislature in April, but did not accompany Kim on his summit with Russian President Vladimir Putin later that month.

The Chosun Ilbo story, which Reuters was unable to independently confirm, also said North Korea executed its working-level nuclear envoy to the United States, Kim Hyok Chol, as part of a purge of officials who steered negotiations for the collapsed summit in February.

Officials who worked with Kim Yong Chol have been out of the public eye since the summit, while seasoned diplomats who appeared to have been sidelined, including Vice Foreign Minister Choe Son Hui, were seen returning to the spotlight. (Reporting by Joyce Lee; Additional reporting by David Brunnstrom; Editing by Peter Cooney)