Japan confirmed that North Korea had conducted a nuclear test on Sunday, and lodged a formal protest with Pyongyang after a major explosion at the isolated nation's main test site.

"The government confirms that North Korea conducted a nuclear test after examining information from the weather agency and other information," Japanese foreign minister Taro Kono told reporters.  

He said the government registered a protest with the North Korean embassy in Beijing prior to the confirmation, calling any test "extremely unforgivable".

Source: AFP