North Korea has claimed to have carried out its first hydrogen bomb test, a development which has sparked global condemnation from world leaders.

The surprise test was reportedly ordered by North Korean leader Kim Jong-Un and came just two days before his birthday.

"The republic's first hydrogen bomb test has been successfully performed at 10:00am on January 6, 2016, based on the strategic determination of the Workers' Party," a state television news reader announced.

"With the perfect success of our historic H-bomb, we have joined the rank of advanced nuclear states," the announcer said, adding that the test was of a "miniaturised" device.

Australian Foreign Minister Julie Bishop said the reported test violated unanimous United Nations Security Council Resolutions.

"Australia condemns in the strongest possible terms the provocative and dangerous behaviour of the North Korean regime, which claims to have detonated a nuclear bomb today," the statement from Ms Bishop’s office read.

"North Korea's ongoing development of nuclear weapons and ballistic missiles, and its proliferation of sensitive technologies, threaten the peace and security of Australia’s friends and partners in our region and beyond.

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

The announcement was made on state television news.

Ms Bishop called on the UN Security Council to provide a "strong response" to the tests, and said Australia would voice its concerns with the North Korean regime directly.

White House National Security Council spokesman Ned Price said he could not confirm the H-bomb claim, but promised the US would "respond appropriately to any and all North Korean provocations".

South Korea has "strongly condemned" the test and warned Pyongyang that it would be made to "pay the price" for ignoring international opinion.

Japanese Prime Minister Shinzo Abe also called it a "serious threat" to Japan and a "grave challenge" to nuclear non-proliferation efforts.

Only last month, during remarks made during an inspection tour, Kim had suggested Pyongyang had already developed a hydrogen bomb - although the claim was greeted with scepticism by international experts.

A hydrogen, or thermonuclear device, uses fusion in a chain reaction that results in a far more powerful explosion.

"The latest test, completely based on our technology and our manpower, confirmed that our newly-developed technological resources are accurate and scientifically demonstrated the impact of our miniaturised H-bomb," the TV announcer said.

The announcement will leave the international community scrambling to verify the accuracy of the North's claims.

But experts have expressed their doubts at the veracity of North Korea’s claims.

"The seismic data that's been received indicates that the explosion is probably significantly below what one would expect from an H-bomb test," Australian nuclear policy and arms control specialist Crispin Rovere said.

"So initially it seems to be that they've successfully conducted a nuclear test but unsuccessfully completed the second-stage hydrogen explosion."

Most experts had assumed Pyongyang was years from developing a thermonuclear bomb, while assessments were divided on how far it had gone in mastering the technology to miniaturise a device that could fit on a ballistic missile.

While vowing to stick by a no-first use policy, today's statement said Pyongyang would continue to pursue an advanced nuclear strike capability.