Brussels, Belgium: The European Union condemned North Korea's claimed hydrogen bomb test on Wednesday as a "grave violation" of a UN ban on its development of nuclear weapons and a threat to the region.
"If confirmed, this action would represent a grave violation of (North Korea's) international obligations not to produce or test nuclear weapons, as determined by several United Nations Security Council Resolutions, and a threat to the peace and security of the entire northeast Asia region," EU foreign affairs head Federica Mogherini said in a statement.
Mogherini urged North Korea "to cease this illegal and dangerous behaviour" and to return to what are known as the Six Party talks -- grouping North and South Korea, China, Russia, the United States and Japan -- on Pyongyang's nuclear programme and the future of the divided Korean peninsula.
She said she would contact the South Korean and Japanese foreign ministers to discuss the next steps as the UN Security Council prepared to take up the issue later in the day.
North Korea said earlier it had carried out a successful miniaturised hydrogen bomb test which put it in "the rank of advanced nuclear states." Pyongyang has carried out three previous nuclear tests, in 2006, 2009 and 2013.
The EU established diplomatic relations with Pyongyang in 2001 but ties remain minimal. Following the earlier tests, the 28-nation bloc imposed a series of trade bans and asset freezes against some 60 North Korean individuals and entities.