Japanese Prime Minister Shinzo Abe on Wednesday condemned a hydrogen bomb test conducted by the Democratic People's Republic of Korea (DPRK), saying the test was a "significant threat," according to Japan's public broadcaster NHK.

Japan has held its national security council meeting immediately after a 5.1-magnitude quake was detected at around 10:30 a.m. local time (0200 GMT) in the northeastern part of the DPRK.

The DPRK's official media said an hour later that the country has successfully conducted its first hydrogen bomb test. The DPRK had conducted three nuclear tests in 2006, 2009 and 2013.

"The hydrogen bomb test is a significant threat to Japan's national security and is unacceptable," the prime minister told reporters, adding Japan will consider sanctions against the DPRK as its nuclear test violates UN Security Council's relevant resolutions.

Japan lifted part of its own sanctions against the DPRK since the two countries reached an agreement that Pyongyang agreed to reinvestigate the whereabouts of Japanese nationals it allegedly abducted some four decades ago.

Abe also said Japan will work with the United States, South Korea, China and Russia to cope with the issue.

Meanwhile, Japanese Foreign Minister Fumio Kishida will hold talks with US Ambassador Caroline Kennedy over the nuclear test.