North Korea says its leader Kim Jong Un has inspected nuclear weapon-related sites, including a uranium enrichment facility, and instructed officials to boost the production of nuclear weapons.

Friday's edition of the Rodong Sinmun, the ruling Workers' Party newspaper, carried reports on Kim's visits to the Nuclear Weapons Institute and the production base of weapons-grade nuclear materials.

This is the first time North Korea has reported on the leader's inspection of a uranium enrichment site.

The paper said Kim instructed officials to increase the number of centrifuges and push forward plans to introduce a new type of centrifuge. It said Kim stressed the need to further strengthen the foundation for producing weapons-grade nuclear materials.

A photo showed Kim inspecting the enrichment facility.

North Korea apparently intends to stress before the US presidential election in November that it plans to further advance its nuclear development.

North Korea also announced on Friday that it has developed a new type of 600-millimeter multiple rocket launcher, and conducted test-firing that was observed by Kim.

This appears to be a reference to the multiple short-range ballistic missiles that the North fired on Thursday.

North Korea reportedly calls these missiles "super-large rockets."