The Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) said on Tuesday that an unusual seismic event was detected in the Democratic People's Republic of Korea (DPRK).

Tibor Toth, executive secretary of CTBTO, said the seismic event's location was roughly congruent with nuclear tests carried out by North Korea in 2006 and 2009.

"If confirmed as a nuclear test, this act would constitute a clear threat to international peace and security." he said.

"I recall UN Security Council resolution 1874, adopted on 12 June 2009, which condemned the nuclear test conducted by the DPRK in May 2009, and called upon the DPRK to join the Treaty as soon as possible." he added.

The DPRK said it has "successfully" conducted its third underground nuclear test on Tuesday.

Its official KCNA news agency said the test was done in a "safe and perfect" way with a smaller and light A-bomb unlike the previous ones, yet with great explosive power.