North Korea is building a mobile long-range missile launcher system that can move along the country's railroad tracks, the U.S.-based Radio Free Asia reported Wednesday, citing sources in the communist country.

A North Korean resident in Kangwon Province told RFA that North Korean engineers have been working on the mobile missile system since May at a state-run motor vehicle factory.

The plant is under the supervision of the North's Second Economic Commission that is in charge of the ammunition industry.

The unidentified North Korean source said that technicians have built some six railway-mounted launcher vehicles per month.

Another source in North Hamgyong Province also said he heard the government is manufacturing vehicles to launch a long-range missile that can move over the country's railways.

According to the source, the North's Second Economic Commission is overseeing the production of mobile missile launchers as North Korean leader Kim Jong-un emphasized in March the need to diversify the country's nuclear attack capability against the enemy.

"North Korea has no other way but to produce such launchers because China has suspended the exports of large-scale vehicles capable of handling mobile missile launchers," the informant said.

Other North Korean sources claimed the mobile missile launchers moving along railroads are not effective in the strategic aspect because of the country's dilapidated railroad system. (Yonhap)