Tokyo, Sep 9 (IANS): Japanese Prime Minister Shinzo Abe on Friday said the nuclear test conducted by North Korea was unacceptable and would be protested.

Abe also said that Japan would liaise closely on the matter with the US and South Korea as the situation unfolds, Xinhua news agency reported.

The Japanese Prime Minister said he had instructed all relevant officials in his office and applicable ministries to gather more information about North Korea's testing of a nuclear device.

His instructions followed Japan Meteorological Agency (JMA) detecting an artificial earthquake centred in North Korea close to a previous test site, which it believes may have been a nuclear test.

An artificial quake of magnitude 5 was detected around 9.30 a.m. at North Korea's main Punggye-ri nuclear test site. The US Geological Survey said the tremor was a 5.3-magnitude earthquake.

In a press conference, Chief Cabinet Secretary Yoshihide Suga said on Friday the government is currently gathering more information about the possible nuclear test.

Foreign Minister Fumio Kishida also said that Japan would convene an emergency meeting of its National Security Council (NSC) to discuss issues relevant to the incident.

Government officials here have also said that if the test is confirmed, Japan will call for an emergency UN Security Council meeting on the matter.

North Korea is banned by UN sanctions from any tests of nuclear or missile technology. It conducted a fourth nuclear test in January this year.