The H-bomb can be detonated even at high altitudes for extremely powerful EMP attacks, it added.

"All components of the H-bomb were homemade, and all the processes ranging from the production of weapons-grade nuclear materials to precision processing of components and their assembling were put on the Juche basis, thus enabling the country to produce powerful nuclear weapons as many as it wants, " it added. Juche is its state ideology meaning self-reliance.

In January 2016, North Korea conducted its fourth nuclear test, which Pyongyang claimed to be a successful test of a hydrogen bomb.

Outside experts said that it appeared to be a test of a boosted fission weapon, rather than an H-bomb.

North Korea has carried out five nuclear tests since 2006, including two last year. It is seeking to develop a nuclear weapon small enough to be mounted on an ICBM.

The announcement came amid heightened tensions after North Korea fired an intermediate-range ballistic missile over Japan last week.

In July, North Korea tested two ICBMs, which analysts say could put much of the US mainland within range, including Los Angeles and Chicago. (Yonhap)