Seoul,on Friday, North Korea has conducted its fifth nuclear test, hours after a blast was detected by the seismic monitors near the secretive country’s nuclear test site, and triggered tensions in neighbouring South Korea and Japan.

According to the sources, "Our nuclear scientists staged a nuclear explosion test on a newly developed nuclear warhead at the country's northern nuclear test site”.

"Our... party sent a congratulatory message to our nuclear scientists... for conducting the successful nuclear warhead explosion test," it added.

A 5.3 magnitude artificial earthquake was detected by seismic monitors near the North's Punggye-ri nuclear test site, with almost identical patterns to previous detonations, says a South Korean expert.

South Korea's President Park Geun-Hye said today, condemning the move as an act of self-destruction that would deepen its isolation.

A defence ministry spokesman in Seoul said, "We believe that it was a nuclear test. We are trying to figure out whether it was successful. The blast measured about 10 kilotonnes".

"The 10-kilotonne blast was nearly twice the fourth nuclear test and slightly less than the Hiroshima bombing, which was measured about 15 kilotonnes," said Kim Nam-Wook from the South's meteorological agency said.

Environment ministry of China began emergency radiation monitoring along its borders with North Korea in northeast China, says reports.