North Korea confirmed that it conducted a "nuclear warhead explosion" test on Friday morning. Pyongyang said the test – the fifth one this year – was a response to the international sanctions imposed against the country and was meant to "counter US hostility". It added that they will continue such tests to "strengthen the quantity and quality" of its nuclear arsenal, North Korea's state television reported, according to AP.

According to South Korea's Office of the Joint Chiefs of Staff, "artificial seismic waves" from a quake measuring 5 on the Richter scale was detected near the Punggye-ri test site. An official from South Korea's Defence Ministry said they had detected an explosive yield of about 10 kilotons.

This was the largest of the past four tremors that were caused by North Korea's nuclear activities. Monitoring services from Europe, the United States and Japan also detected similar seismic activity, AP reported. The US Geological Survey centre called it an "explosion" on its website.

The nuclear test comes on the occasion of the 69th anniversary of the founding of North Korea by Kim Il-sung, grandfather of current leader Kim Jong-un. The nuclear test comes even after the United States and United Nations Security Council imposed stringent sanctions against Pyongyang in March, in response to a hydrogen bomb test North Korea conducted in January.