State media has made the announcement on the test.

The country made the announcement after a 5.1 magnitude earthquake was detected close to nuclear test site.

 According to USGS website, an earthquake measuring 5.1 on the Richter Scale hit North Korea with the epicentre being 19 kms east-north-east of North Korea's Sungjibaegam town.

Japan and South Korea earlier in the day   claimed that the earthquake which hit  North Korea on Wednesday might be the result of a nuclear test conducted by the nation.

Kyodo News of Japan reported: "The Japanese government said there is a possibility that the seismic event was caused by a nuclear test and that it is gathering and analyzing information."

South Korea has called it an 'artificial quake'.

"Considering the waveform and the amplitude of the earthquake, it seems certain that it was an artificial quake," a  South Korean meteorological administration official was quoted as saying by Yonhap News Agency.

"(We are) going through a thorough analysis based on the high possibility of it being a nuke test," the official said.