North Korea staged a huge rally in its capital Pyongyang on Thursday to celebrate its third nuclear test conducted two days ago, hailing it as a "success," according to the North's media.

Photos provided by the North's Korean Central News Agency showed huge crowds cheering to mark the underground atomic test, which has drawn a chorus of worldwide condemnation and warnings of tougher sanctions against the North.

It was the first nuclear test under young leader Kim Jong-un, who took the helm of North Korea in late 2011 after the death of his father Kim Jong-il.

Kim Jong-un didn't appear at the rally, but Kim Ki-nam, a secretary of the ruling Workers' Party, told the crowd that Tuesday's nuclear test was a result of a "resolute" decision by the new leader, according to the North's Korean Central Broadcasting Station.

Describing the third test as a "splendid national achievement," the party secretary who handles propaganda, said that the latest nuclear test was a "stern and fair self-defense measure to cope with a hostile policy by the U.S. towards North Korea."

The third nuclear test "was achieved thanks to the Great Marshal Kim Jong-un's resolute decision," the party secretary said, adding that the leader "wisely led" the test.

North Korea conducted two previous nuclear tests in 2006 and 2009.

South Korean nuclear scientists said they have been unable to detect any radioisotopes from the country's nuclear test, complicating efforts to confirm what kind of fissile material was used.  

The North's claims that it used a "miniaturized" device, which could mean that Pyongyang might be capable of making nuclear weapons small enough to fit on a missile.(YONHAP)