Kim, 66, is lucid and has no trouble speaking, according to a high-level Chinese official who met in recent weeks with the North Korean leader in Pyongyang, the South Korean newspaper Chosun Ilbo reported, citing an unidentified source in Beijing.
But the Chinese official had predicted that Kim would miss Tuesday's anniversary ceremony, the official was quoted as saying. The report did not give further details.
Kim is the object of an intense personality cult in the totalitarian nation, and the sight of him with spasms before hundreds of thousands of people would have been an embarrassment for the regime.
The South Korean government has confirmed that Kim suffered a stroke but said he is recovering and remains in control of the country. South Korea's National Intelligence Service and the Unification Ministry said they could not comment on the Chosun Ilbo report.
South Korea's Yonhap news agency quoted an unnamed government official on Friday as saying the government understands Kim has recovered enough to brush his teeth on his own.
The spy agency and the Unification Ministry said they were aware of the Yonhap report but could not confirm it.
South Korean media have reported that Kim collapsed around Aug. 15. His absence from Tuesday's anniversary ceremony intensified speculation that the leader - long believed to be suffering from diabetes and heart disease - was seriously ill. He had been out of the public eye for weeks and foreign doctors were rumored to have been flown into Pyongyang to treat him.
But Seoul's presidential Blue House said Wednesday that Kim was not considered to be "in a serious condition."
Kim is "recovering fast," has no trouble communicating and speaking and is "able to stand if assisted," South Korean ruling party lawmaker Lee Cheol-woo said in a radio interview Thursday. Lee is a leader of the parliamentary intelligence committee, which was briefed by the spy agency the previous day.
North Korea's state media have made no mention of Kim's health. On Friday, the country's main Rodong Sinmun newspaper carried a lengthy editorial calling for the impoverished population to unite behind Kim, who is revered as the "Dear Leader" or "Dear General."
"Our dignified republic exists because Dear General exists," the newspaper said, according to the official Korean Central News Agency. "All party members and workers should further unite around the revolutionary leadership."
Kim's health has been a focus of intense interest because his fate is believed to be closely tied to that of the totalitarian state he has ruled since his father, North Korean founder Kim Il Sung, died in 1994.
Kim's health condition could further complicate six-nation talks on North Korea's nuclear disarmament which recently hit a snag over how to verify the country's nuclear programs.
South Korea's top nuclear envoy, Kim Sook, told reporters Friday that Seoul officials were discussing the matter with their counterparts in the U.S. and China.
"We're carefully thinking about how this will affect the six-party talks," Kim said.
South Korea said last week that North Korea had begun restoring its nuclear facilities, apparently to protest delays by Washington in removing the North from a list of terrorism-sponsoring countries. North Korea stopped disabling its Yongbyon nuclear complex in mid-August.
The U.S. has said North Korea must agree to an international plan to verify the account of its nuclear programs it submitted in June if it wants to be removed from the terrorism list.