North Korean leader Kim Jong Il is alive but seriously ill, a news report said Wednesday, amid mounting speculation over the leader's health after he missed a key national ceremony.

South Korea's Yonhap news agency cited an unidentified South Korean government official as saying Kim appeared to have "collapsed," a term that in the Korean language is used when a person becomes suddenly ill due to causes including stroke.

The official stressed that it is certain that Kim has not died, Yonhap said.

The report did not give further details.

Kim did not appear at a parade commemorating North Korea's founding 60 years ago Tuesday, one of the country's most celebrated holidays along with the birthdays of Kim and his late father and founding leader, Kim Il Sung.

Western intelligence officials have said Kim's failure to appear at Tuesday may indicate that he is seriously ill and could even have had a stroke, though they cautioned that such speculation has not been independently confirmed.

On Wednesday, South Korean President Lee Myung-bak convened an emergency meeting in Seoul with senior aides to discuss the situation, an official at the presidential Blue House said.

The official, who spoke on customary condition of anonymity citing office policy, could not give further details because the meeting was still under way.

The 66-year-old Kim, who has been rumored to be in varying degrees of ill health for years, took over the reclusive state upon the death of his father 14 years ago in communism's first hereditary transfer of power. The younger Kim attended the parade on the 50th and 55th anniversaries and was widely expected to do so this year as well.