North Korea says it has successfully tested a nuclear weapon that could be loaded onto a long-range missile.

The DPRK officials said its sixth nuclear test was a “perfect success”, hours after seismologists had detected an earth tremor, assessed as ‘anthropogenic’.

Pyongyang said it had tested a hydrogen bomb – a device many times more powerful than an atomic bomb.

Analysts warned the claims should be treated with caution, but its nuclear capability is clearly advancing.

North Korea last carried out a nuclear test in September 2016. It has defied UN sanctions and international pressure to develop nuclear weapons and to test missiles which could potentially reach the mainland US.