Comments from around the world on North Korea's announcement that it conducted its fourth nuclear test, and its first of a hydrogen bomb, yesterday:

PARK GEUN-HYE - South Korean president:

"It's not only grave provocation of our national security, but also an act that threatens our lives and future. It's also a direct challenge to world peace and stability."

A North Korean -

television anchor:

"The Republic (referring to North Korea), as a responsible nuclear weapon holder, will neither use nuclear weapons first nor transfer (nuclear) related means and technology under any circumstances as already declared unless aggressive, hostile forces infringe upon our autonomy. There can neither be suspension of nuclear development nor nuclear dismantlement unless the US rolls back its vicious hostile policy towards North Korea."

MELISSA HANHAM -

senior researcher at the James Martin Center for Nonproliferation Studies at the Middlebury Institute for International Studies in Monterrey, California.

"I'm pretty sceptical. ... The seismic data indicates it would be very small for a hydrogen test.

"It would be very, very remarkable if they had achieved it already. ... It seems just too soon to have this big technical achievement. But North Korea has always defied expectations."

PHILIP HAMMOND - British foreign secretary:

"If a nuclear device has been detonated by North Korea, this is a grave breach of UN Security Council resolutions and a provocation which I condemn without reservation.

"I have discussed this matter today in Beijing with my Chinese counterpart, State Councillor Yang Jiechi, and we have agreed to work with other members of the UN Security Council towards a robust international response."

SHINZO ABE - Japanese prime minister:

"North Korea's nuclear test this time is a major threat to our nation's safety. This absolutely cannot be tolerated and we strongly condemn this act. Going forward, our country, as a non-permanent member of the United Nations Security Council, will coordinate with the United States, South Korea, China and Russia to take resolute measures."

JULIE BISHOP - Australian foreign

minister:

"Today's nuclear test confirms North Korea's status as a rogue state and a continuing threat to international peace and security."

HUA CHUNYING - spokeswoman for China's Ministry of Foreign Affairs:

"The Chinese government firmly opposes this nuclear test by North Korea. We surely will summon North Korean senior officials and the ambassador to lodge our solemn protest."

LASSINA ZERBO -

executive secretary of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization:

"If confirmed as a nuclear test, this act constitutes a breach of the universally accepted norm against nuclear testing; a norm that has been respected by 183 countries since 1996. It is also a grave threat to international peace and security. ... I sincerely hope that this will serve as the final wake-up call to the international community to outlaw all nuclear testing."