North Korean leader Kim Jong-un has been selected to represent the military in the upcoming party congress in May, the country's state-run media said Thursday, as Pyongyang moves toward its first party congress in more than 30 years.

Military representatives of the Workers' Party of Korea (WPK) unanimously made the decision in their two-day gathering from Tuesday to Wednesday, according to the Rodong Sinmun, the North's main newspaper.

It said that the North's leader was selected as a representative of the party event, without unveiling how many representatives they chose overall.

North Korea is set to convene the first party congress, the highest-level political guidance body, in more than 30 years in early May.

Hwang Pyong-so, director of the general political bureau of North Korea's armed forces, hailed Kim's contributions to building North Korea into "a world-class military power" and "one of nuclear powers" in his speech marking the latest decision.

North Korea is stepping up efforts to glorify the young leader in the run-up to the party congress, which is expected to focus on solidifying Kim's one-man leadership.

The congress will likely serve as a key event that will reveal the North Korean leader's policy direction in his fifth year in power. Kim inherited power following the sudden death of his father Kim Jong-il in late 2011.

The North is in the process of selecting delegates to be sent to the party event. The WPK's city and county committees have picked representatives, to be followed by a similar process to choose delegates in provincial areas.

At the congress held in 1980, about 3,000 representatives were selected to take part in the critical event.

"The pace of the North's delegate selection looks considerably slower this time than that shown back in 1980 if the congress is to be held in early May," said an official at Seoul's unification ministry.

Seoul's spy agency said the event is likely to be held on May 7 though Pyongyang has yet to publicly announce the date for the event. (Yonhap)