SEOUL • North Korea has condemned a looming South Korea-United States joint military exercise as a "declaration of war" and boasted of its ability to make retaliatory strikes against Seoul and the White House.

The annual two-week Ulchi Freedom exercise, which kicks off on Monday, involves tens of thousands of troops in what is a largely computer-simulated rehearsal for a North Korean invasion.

It is one of a number of annual joint drills that Washington and Seoul insist are purely defensive in nature, but which Pyongyang condemns as provocative rehearsals for a full-scale attack on the nuclear-armed North.

Yesterday, the North's Foreign Ministry insisted that the drill be called off immediately and warned Washington that the US will be responsible for "all the consequences" if it went ahead.

A spokesman said Pyongyang will take "all necessary measures" in the face of US "nuclear provocations", reported the North's official KCNA news agency.

A separate statement by North Korea's Committee for the Peaceful Reunification of Korea, which oversees cross-border issues, denounced Ulchi Freedom as a "drill for a surprise nuclear war" against the North.

Echoing a threat it has made repeatedly in the past, the North Korean committee said South Korea and the US should be aware that their "strongholds of aggression and provocation" - including the White House and the presidential Blue House in Seoul - were within range of the North's "ultra-precision" military weapons.

North Korea has an extensive missile development programme to complement its nuclear weapons strategy, although experts are divided on how advanced its delivery systems are.

In May, the North claimed to have successfully test-fired a submarine-launched ballistic missile - a technology that could eventually offer a survivable second-strike capability.

But experts questioned the authenticity of the May test, saying that photos of the launch might have been digitally manipulated.

Exercise Ulchi Freedom will kick off amid elevated cross-border tensions, following the recent mine attack that maimed two South Korean soldiers.

Pyongyang has yet to react to the charge that it was responsible, but the South has already resumed propaganda broadcasts across the border, using batteries of loudspeakers that had lain silent for more than a decade.

AGENCE FRANCE-PRESSE