The UN Security Council is considering imposing further sanctions on North Korea after it carried out a nuclear test, the British ambassador said Wednesday.

"We will be working with others on a resolution on further sanctions," Ambassador Matthew Rycroft told reporters.

The United States, Japan and other members of the 15-member council were working on a draft text that would strongly condemn what Pyongyang has called a hydrogen bomb test, diplomats said. 

"We have no information on the type of device tested," said Rycroft, but he added: "Any nuclear test is a clear violation of UN Security Council resolutions."

North Korea said it had carried out a "successful" miniaturized hydrogen bomb test -- a shock announcement that, if confirmed, would massively raise the stakes in the hermit state's bid to strengthen its nuclear arsenal. 

The announcement triggered swift international condemnation but also skepticism, with experts suggesting the apparent yield was far too low for a thermonuclear device.

The council was set to hold a closed-door meeting from 1600 GMT to discuss the nuclear test, at the request of the United States and Japan.

A senior UN diplomat said there would be a strong statement of condemnation from the council and work would begin on a draft resolution that would provide for targeted sanctions.

It was unclear when a vote on the draft resolution would take place.

Three previous tests in 2006, 2009 and 2013 triggered waves of UN sanctions.

"The latest test is yet another example of the DPRK regime's reckless challenge to international norms of behavior," said Rycroft.