Recent satellite images show that North Korea may haven taken steps to hide a facility that the US believes is used to store nuclear weapons, CNN reported Tuesday.

The images, captured by a US space technology company, Maxar, on Feb. 11, show new structures at the North's Yongdoktong site to conceal entrances to two underground tunnels, the report said.

"Yongdoktong has been previously identified by US intelligence as a suspected North Korean nuclear weapons storage facility and is still believed to be used for that purpose," CNN reported, quoting an unidentified US intelligence official.

CNN added the site has been widely known to US experts and officials for years and that it has been identified as a nuclear weapons storage facility.

Still, the network noted the true intention or purpose of the newly added structure needed to be examined.

"The timing of the movements at Yongdoktong is noteworthy but requires some examination because North Korea's actions can never be taken at face value," it quoted an unidentified former US intelligence official as saying.

"Recent construction at the site will certainly catch the attention of US intelligence agencies as they carefully monitor sites suspected to be part of Pyongyang's nuclear weapons program," it quoted others as saying.

The Biden administration is currently reviewing its North Korea policy that it says will lead to a new US approach toward the North and its nuclear issue.

Pyongyang is widely suspected of having continued developing its nuclear and long-range missile capabilities despite its self-imposed moratorium on nuclear and long-range missile testing since November 2017.

The North conducted its sixth and latest nuclear test in September 2017. (Yonhap)