North Korea has conducted a sixth nuclear test, the Japanese government said, a move the United States and its allies in the region are likely to view as a major provocation.

Seismological data from the United States Geological Survey (USGS) showed that an explosion caused a 6.3-magnitude tremor in the country’s northeast, not far from the country’s Punggye-ri nuclear test site.

North Korea state television said Pyongyang had tested a hydrogen bomb, and the test was a ‘complete success’.

Japan later confirmed that it was a nuclear test and lodged an official protest through North Korea’s embassy in Beijing.

“After analysing information from the Japan Meteorological Agency and others on the recent earthquake, the government has determined that North Korea has carried out a nuclear test,” Taro Kono, the Japanese foreign minister, told reporters after a meeting of the National Security Council on Sunday afternoon.