Story highlights The last congress of the Workers' Party of Korea was in 1980

Kim Jong Un's father Kim Jong Il was announced then as the next leader of North Korea

Party congresses are momentous occasions in North Korea

Seoul, South Korea (CNN) North Korea has announced plans for a rare, potentially significant occasion for next year. It will convene its seventh communist party congress.

The Workers' Party of Korea hasn't held one since 1980, and that one peaked with the announcement that Kim Jong Il, the father of the country's current leader, would take the reigns of power. The next congress will come in May, North Korea's official news agency KCNA reported on Thursday.

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Why the Political Bureau, which Kim Jong Un heads, called the congress has triggered speculation. They were once more common but ceased once his father took power.

The official reason for the congress given in KCNA's report was that it was "reflecting the demand of the party and the developing revolution."

The congress may be intended to bolster the perception that Kim has a stable hold on power, said Yang Moo-jin from South Korea's University of North Korean Studies. Kim may announce economic reforms or new diplomatic relations.

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