12 February 2013 Last updated at 06:43 ET
A KCNA newsreader announced the test, saying it had "great
North Korea has carried out its
third, most powerful nuclear test despite UN warnings, and said "even stronger"
action might follow.
It described the test as a "self-defensive measure" necessitated by the
"continued hostility" of the US.
Its main ally, China, criticised the test, which was condemned worldwide.