North Korean leader Kim Jong-un has called for a "drastic boost" of the country's missile production capacity, the North's state media said Monday, as South Korea and the United States plan to stage joint military drills later this month.

Kim made the remarks during a two-day visit to major factories that produce strategic missiles, rocket launchers and other military weapons on Friday and Saturday, according to the North's official Korean Central News Agency.

The visit came less than a week after the North Korean leader conducted a "field guidance" of major munitions factories as South Korea and the United States plan to hold their annual Ulchi Freedom Shield exercise later this month, which Pyongyang has denounced as a rehearsal for an invasion of the North.

It also came just days after Kim presided over an enlarged meeting of the Central Military Commission of the ruling Workers' Party of Korea, calling for preparing for a possible war in an "offensive" manner.

"He set forth an important goal to drastically boost the existing missile production capacity... so as to mass-produce missiles as required by the system of the expanded and strengthened frontline units and missile units and by the operational plans," the KCNA said.

Kim was also quoted as saying that the North's Korean People's Army should be equipped with an "overwhelming military force" for "coping with any war at any moment so as to prevent the enemies from daring use their armed forces, and surely annihilate them if they launch an attack."

During his visit to a factory producing tactical missile transporter-erector-launchers, Kim called for the production of "more modern and highly efficient TELs substantially conducive to the army's perfect war preparations," according to the KCNA

Photos released by state media show Kim driving what the North called a "newly-developed utility combat armored vehicle" during his visit to one of the factories. (Yonhap)