North Korea's ruling party plans to convene the congress for the first time in more than three decades in early May, Pyongyang's state media said Friday, in what could be the latest move to strengthen leader Kim Jong-un's grip on power.

The political bureau of the central committee of Workers' Party of Korea has decided to hold the seventh congress of the party in May, the Korean Central News Agency said, without providing a specific date or agenda.

It marks the first party congress since October 1980, as well as the first since Kim took power in late 2011.

"We are faced with the heavy yet sacred task to bring about a great upswing in the building of a thriving socialist nation," the party's political bureau said, according to the KCNA.

A South Korean official said on condition of anonymity the North's move seems to be aimed at assessing its accomplishments and to set a line of policy.

"The government is closely watching the North's decision. North Korea seemed to make such a decision by taking into account its internal affairs and foreign relations," ministry spokesman Jeong Joon-hee said in a regular press briefing.

Former North Korean leader Kim Jong-il, the late father of the current leader, advocated a military-first, or "songun," policy by operating the National Defense Commission as the main decision-making body.

But the young leader has shifted his focus to the party since inheriting power in 2011 following the sudden death of his father.

Kim is pursuing a dual policy of developing nuclear weapons and boosting the country's ailing economy, a policy South Korea and the U.S. have warned is a dead end for the country.

The North conducted a massive military parade on Oct. 10 to mark the party's 70th anniversary. Kim delivered a rare public speech ahead of the parade where the North Korean leader showed his care for people.

Experts said that the move could herald the full-fledged start of Kim's era amid prospects that the North's leader is likely to unveil his new polices or conduct a major reshuffle, based on his consolidated power.

"Kim is expected to push for an overhaul for the party's leadership and personnel reshuffle at next year's congress," said Cheong Seong-chang, a senior researcher at the Sejong Institute.

"His grip on power will likely be strengthened further."

The first party congress was held in August 1946 under the regime of Kim Il-sung, the North's late founder and the current leader's grandfather.

North Korea used the WPK's congress as a chance to announce new policy lines, including the five-year plan for economic development in 1956. At the sixth congress in 1980, Kim's father, Kim Jong-il, was confirmed as a successor to the North's founder.

North Korea has seen its isolation deepening as it is under heavy sanctions by the U.N. Security Council due to its nuclear and missile tests.

On the diplomacy front, North Korea's relations with China have been frayed since the North's nuclear test in early 2013.

But the North and its treaty ally China displayed a show of solidarity during the military parade as Liu Yunshan, a top Chinese official, attended it in Pyongyang, standing next to Kim. (Yonhap)