A hydrogen bomb test which North Korea claimed it has conducted is a “provocation” and a “grave breach” of UN Security Council resolutions, Philip Hammond said.
Mr Hammond, who is currently on an official visit to China, tweeted: “If North Korean H-bomb test reports are true, it is a grave breach of UNSC resolutions & a provocation which I condemn without reservation.”
The news of the “miniaturised” hydrogen bomb test was unexpected, as no mention has been made in leader Kim Jong Un’s New Year speech.
The US Geological Survey measured an earthquake with a magnitude of 5.1 – bigger than the three previous bombs in 2013, 2009 and 2006.
South Korea’s weather agency Korea Meterological Administration said the quake originated 30 miles north of Kilju, where North Korea’s main nuclear test site is.
News of the bomb test has been met with widespread condemnation. South Korea suggested its rival may face further UN sanctions as a result.
Japanese Prime Minister Shinzo Abe said of the bomb test: “We absolutely cannot allow this, and condemn it strongly.” Hydrogen bombs are generally more powerful and difficult to make than atomic bombs.