North Korea is reportedly set to conduct a long-range missile test launch from its northwestern Sohae satellite launching station of Tongchang-ri, Japan's Kyodo news agency has reported.
Images taken by US spy satellites have also shown increased activity at the site involving movement of rocket-related equipment, fuel and personnel.
Screens were said to be erected around the base to shield the activities from being spied on by foreign satellites.
The site is also reportedly fortified with automated systems, and rails are set up to move rocket components quickly for final assembly and launch, according to Yonhap news agency.
An unnamed Japanese official has revealed that the images confirm North Korea is gearing up for a missile launch.
At a regularly-scheduled press conference, South Korean Defense Ministry spokesman Kim Min-Seok was quoted as saying: "It will be a direct violation of (a UN Security Council resolution) and ... will be a severe provocation and threat against peace and stability of South Korea, northeast Asia and the world. It is our government's official position that North Korea should not proceed with such provocative acts."
Earlier this month, North Korea claimed to have tested a hydrogen bomb, which was dismissed by skeptics, stating that the nation was not yet technically capable enough to conduct such tests.
Additionally, the nation also confirmed that it tested a submarine-launched ballistic missile. The tests prompted UN Security Council members to impose sanctions against the country, which is already under sanctions for its nuclear and missile programmes.
It last launched a long-range rocket in 2012, which was referred to as a communications satellite.