UN Secretary General Ban Ki-Moon plans to visit the Soviet-era Semipalatinsk nuclear test facility during his visit to Kazakhstan next month, the United Nations Development Program said on Tuesday.

"During his visit the UN secretary general... will visit the Semipalatinsk region and especially the territory of the former nuclear testing ground," the UNDP's Kazakhstan office said in a statement.

Ban is due to visit the vast Central Asian country on April 6-7.

The Semipalatinsk testing facility in northeastern Kazakhstan was the main location for Soviet nuclear tests for four decades and the area is highly polluted by radiation.

The first Soviet nuclear test took place there in 1949 and by the time the site was closed in 1989 at least 468 nuclear tests had been carried out, including 55 airborne or above ground explosions.

An estimated 1.6 million people were subjected to radiation during this period due to Soviet authorities' failure to take the necessary measures to protect the population.