North Korea has claimed success in a fifth nuclear test as the hermit state continues to defy UN resolutions.

South Korea believes this is the North's biggest-ever test, and a 5.3 magnitude-tremor was detected near their test site.

Since 2006 North Korea has been banned from tests of missile or nuclear technology by the UN.

The test has led to fear over the significant nuclear advances the rogue state may have made. North Korean officials have announced the test was for a standardised nuclear warhead which can be mounted on ballistic rockets.

South Korean President Park Geun-hye has called the incident an act of "self-destruction", whilst China's foreign ministry has urged North Korea to avoid any further action.

The US has claimed there will be "serious consequences".

There have been varied estimates of the size of the blast, with South Korea estimating it at around 10 kilotonnes, but other experts have claimed it could have been 20 kilotonnes.