North Korea released a propaganda video Tuesday depicting a mock artillery attack on South Korea's main government buildings including the presidential office Cheong Wa Dae.

The video was published on the North's propaganda website "DPRK Today" under the title "Unless South Korea complies with our ultimatum."

DPRK is the acronym of the North's official name, the Democratic People's Republic of Korea.

North Korea has threatened to take "merciless" action against South Korea unless Seoul offers an apology for its alleged move to strike out at the North Korean leadership.

The 1.28-minute video starts with the North's ultimatum announced on March 26, proceeded by the image of the North Korean army's long-range artillery exercises conducted on March 24.

Then the visual shows the artillery shelling downtown Seoul between Sungnyemun (South Gate) and the National Theater near Namsan Mountain.

A computer graphic shows three shells hitting Cheong Wa Dae, then destroying the government complex in Seoul, U.S. Forces Korea headquarters and the National Intelligence Service.

In a final scene, the video ends with the phrase "Everything will turn into ashes."

Tensions between the two Koreas have been on the rise since Pyongyang carried out its fourth nuclear test in January, and a satellite rocket launch a month later. The rocket launch is viewed by outsiders as a disguised long-range ballistic missile test.

Pyongyang has upped the rhetorical ante in recent weeks, with near daily threats of nuclear and conventional strikes against the South and the U.S. mainland in response to large-scale annual Seoul-Washington military exercises. (Yonhap)