"Our nuclear scientists staged a nuclear explosion test on a newly developed nuclear warhead at the country's northern nuclear test site," a TV announcer said on Friday.

The confirmation came after South Korean authorities said they believed North Korea has conducted a fifth nuclear test — its biggest to date — following the detection of an “artificial earthquake.”

South Korea’s meteorological agency said the magnitude 5.3 quake was detected near North Korea’s Punggye-ri nuclear test site.

“The 10-kiloton blast was nearly twice the fourth nuclear test and slightly less than the Hiroshima bombing, which was measured about 15 kilotons,” said Kim Nam-Wook of South Korea’s meteorological agency.

Reacting to the development, the White House said it was assessing the explosion near North Korea’s nuclear test, but stopped short of confirming a nuclear test.

Earlier on Thursday, North Korea had threatened to continue strengthening its nuclear force in reaction to a United Nations Security Council’s recent statement condemning the country’s latest missile tests.

In January, North Korea said it had detonated a hydrogen bomb with success, its fourth nuclear test, and vowed to build up its nuclear program as “deterrence” against potential aggression from the US and its regional allies.

The UN and the West have imposed a series of sanctions on Pyongyang over its nuclear and missile activities, Press TV reported.

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