North Korean leader Kim Jong-un inspected a machine plant to call for increased production, the country's state-run news agency said Friday in the runup to the ruling party's much-trumpeted congress in May.

The latest field guidance, whose date and exact location were not disclosed by the Korean Central News Agency (KCNA), followed Kim's previous public outing to watch the military's test fire of a surface-to-air guided missile launcher a week earlier.

Kim has made frequent field visits to major military weapons tests and economic sites since late February as the country is moving toward the 7th congress of the ruling Workers' Party of Korea in early May.

It is North Korea's first party congress, the highest-level political guidance body, which adopts or revises the party's fundamental doctrines. The last congress was held in October 1980 under the country's founder and current leader's grandfather Kim Il-sung.

The incumbent leader praised the work the new machine plant achieved and also ordered workers to join efforts to successfully complete the 70-day campaign of hard work, which the ruling party assigned in February in the run up to the important party meeting.

"The machines produced at the plant are profusely paying off in various fields of the national economy," Kim was quoted as saying.

"The key to this success lies in the fact that the plant attached importance to science and technology and closely combined scientific researches with production as intended by the party."

Kim stressed, "The need to give fuller play to their mental power so that they may emerge honorable victors in the 70-day campaign of loyalty," the KCNA said.

Kim's younger sister Kim Yo-jong and other party officials accompanied the leader, according to the mouthpiece news outlet. (Yonhap)