Japan's defence minister on Tuesday said North Korea's latest nuclear test was more powerful than initially estimated, with a yield that was around eight times the size of the bomb detonated over Hiroshima.

North Korea on Sunday triggered global alarm when it blasted what it described as a hydrogen bomb designed for a long-range missile.

Japan's defence ministry had earlier said the bomb had a 70-kiloton yield, based on an estimated magnitude by the preparatory commission for the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO).

But Japanese Defence Minister Itsunori Onodera told reporters Tuesday that his ministry had upgraded its estimate to around 120 kilotons in accordance with an upward revision by the CTBTO.

“We can figure out that the nuclear test displayed a fairly high capability,” Onodera said.

At 120 kilotons, the blast yield would be around eight times more powerful than the 15-kiloton American bomb which destroyed Hiroshima in 1945.

The estimate also exceeded the yield of between 50 and 100 kilotons indicated by United Nations (UN) political affairs chief Jeffrey Feltman at the UN Security Council.

Earlier in the day, Japan's Prime Minister Shinzo Abe called on the international community to form a united front against Pyongyang's provocations.

“Whether we can contain North Korea's outrageous act or not depends on unity among members of the international community,” Abe said when he met visiting Indian Defence Minister Arun Jaitley in Tokyo.

United States (US) Ambassador Nikki Haley told an emergency meeting of the UN Security Council that Washington will present a new sanctions resolution to be negotiated in the coming days, with a view to voting on it next Monday.

But comments by Russian President Vladimir Putin on Tuesday rejecting US calls for more sanctions as “useless” appeared to have widened a split among major powers over how to rein in Pyongyang, pitting Moscow and Beijing against Washington and its allies.