World leaders have reacted with anger after North Korea carried out its fifth and reportedly biggest nuclear test.

The South accused the North's leader Kim Jong-un of "maniacal recklessness".

China "firmly opposed" the test, Japan "protested adamantly" and the US warned of "serious consequences".

Such tests are banned by the UN, but this is the second nuclear test this year, and Kim Jong-un's rhetoric has become increasingly aggressive.

The isolated communist nation has been hit by five sets of UN sanctions since its first test in 2006. Talks involving world and regional powers have failed to rein in the North's nuclear programme.

In its statement announcing the underground test, North Korea expressed anger at the "racket of threat and sanctions... kicked up by the US-led hostile forces" to deny a "sovereign state's exercise of the right to self-defence".

The test came on the country's National Day, which celebrates the founding of the current regime and which is often used as a show of military strength.