GENEVA — A senior North Korean envoy said Thursday that his country was ready to resume six-party talks on its nuclear program, but must maintain its readiness in the face of joint military exercises between the United States and South Korea.

In an interview, North Korea’s ambassador to the United Nations, So Se-pyong, also said that his country was not planning a nuclear test and that reports that its leader, Kim Jong-un, was ill were “fabricated rumors.”

The negotiations over North Korea’s nuclear program have stalled, but in Geneva, Mr. So said, “We are ready,” adding, “I think China and Russia and the D.P.R.K. are ready,” referring to his country, the Democratic People’s Republic of Korea. He continued: “But America, they don’t like that kind of talks right now. Because America does not like that, so that’s why the countries like South Korea, Japan also are not ready for those talks.”

North Korea promised to abandon its nuclear program in 2005, but it appeared to renege on the agreement when it tested nuclear devices in 2006 and 2009.