SEOUL, South Korea — Huge posters plastered across the North Korean capital hailed the nation’s biggest political convention in 30 years as a historic event as the world watched Monday for signs that the country’s next leader was making his public debut.

Party delegates from all corners of North Korea were gathering in Pyongyang, state media said. Thousands practiced waving pink and red plastic flowers in a weekend rehearsal of celebrations at Kim Il Sung Square, China’s Xinhua news agency said.

The capital was festooned with posters urging North Koreans to "make this a festive event that will shine in the history of our country and people." One North Korean professor told broadcaster Associated Press Television News the party meeting marked a "turning point" for the communist nation.

However, there was no confirmation Monday that the convention, slated to take place in "early September," had begun, with the timing kept secret as is typical of the North Korean regime.

The gathering is the Workers’ Party’s first major meeting since the landmark 1980 congress where Kim Jong Il made his public debut as North Korea’s future leader. He took over after his father, North Korea founder Kim Il Sung, died of heart failure in 1994 in what was communism’s first hereditary transfer of power.

Now 68 and reportedly suffering from diabetes and other ailments, Kim is believed to be grooming his youngest son, Jong Un, to take the Kim dynasty into a third generation.

Very little is known about the twentysomething heir apparent said to be his father’s favorite among three sons. His name has never been mentioned in state media, and there are no known photos of him as an adult.

There was speculation that Kim Jong Il took the son to China on a recent surprise trip to introduce him to top Chinese officials, but there was no mention of Jong Un in dispatches in Chinese or North Korean state media.

South Korea’s defense minister said military officials were preparing for any situation that might arise if the succession doesn’t go smoothly.

"I believe North Korea may face many difficulties since Kim Jong Un is a young man, only about 27 years old," Kim Tae-young said Monday at a Seoul forum.

This year’s gathering in Pyongyang is not a top-level party congress but a meeting of party representatives that North Korea’s state-run Uriminzokkiri website said is held "when urgent or extraordinary matters arise."

Dr. Kim Chang Gyong, an assistant professor at the North Korean Academy of Social Science, hinted to APTN that party officials would be addressing an urgent matter.

"I think (the meeting) will serve as an important occasion amid our efforts to build a powerful socialist nation … at a time when there is a historic demand for a new turning point," he said in Pyongyang.

North Korea’s main newspaper described an anticipatory mood in the capital.

"The people’s hearts awaiting the revolutionary, festive occasion heat up due to their joy and happiness," Rodong Sinmun said.

The conference comes amid tensions with Washington and the international community over the North’s nuclear program, as well as a standoff with Seoul over the deadly March sinking of a South Korean warship.

However, the regime announced Monday that a seven-member crew of a South Korean fishing boat seized last month in its waters would be released as a humanitarian gesture.

The impoverished nation is also suffering from the effects of a disastrous attempt at economic reform.

Delegates are expected to elect about 150-250 representatives to the party’s Central Committee, as well as a core group of 30-40 leaders to the key Political Bureau and other departments, analyst Cheong Seong-chang of the Sejong Institute think tank near Seoul said Monday.

He predicted that preliminary sessions will begin Wednesday, with the main session taking place Thursday — the day North Korea celebrates the 62nd anniversary of the founding of the Democratic People’s Republic of Korea, the country’s official name.

South Korean officials said troops, artillery and tanks were massing near the capital in apparent preparation for a military parade, either for the party convention or for a Workers’ Party milestone taking place next month.

Good Friends, a Seoul-based civic group that sends food and other aid to North Korea, said convention registration began Saturday, and delegates were touring historic sites.

At one Pyongyang museum, black-and-white photos depicted the historic Workers’ Party congress of 1980, held at the April 25th House of Culture.

One photo depicted the late Kim Il Sung taking the podium to address delegates, APTN footage showed. Another showed a young-looking Kim Jong Il — with a full head of black hair and slouching slightly in his seat — watching the proceedings intently with a briefcase and sheaf of papers before him.

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Associated Press writers Sangwon Yoon and Ye Sol Lee contributed to this report.