North Korea says it has conducted successful hydrogen bomb test

North Korea on Wednesday made a major announcement saying it has successfully tested a miniaturised hydrogen bomb.

The announcement followed after South Korean officials detected an "artificial earthquake" near North Korea's main nuclear testing site.

The test has likely become the country’s fourth known nuclear test.

According to an AP report, North Korea conducted its third nuclear test in February 2013. A confirmed test would mark another big step toward Pyongyang's goal of building a warhead small enough to be mounted on a missile capable of reaching mainland America's shores.

The report also added that a test would further North Korea's international isolation by prompting a push for new, tougher sanctions at the United Nations, worsening Pyongyang's already bad ties with Washington and its neighbours.

The United States Geological Survey had reported a 5.1 magnitude quake that South Korea said was 49 km (30 miles) from the Punggye-ri site where the North has conducted nuclear tests in the past.

"We suspect a man-made earthquake and are analysing the scale and epicentre of the quake," a Korea Meteorological Administration official told Reuters by phone.

North Korea is known to have conducted three nuclear tests and is under UN sanctions for its nuclear and missile programmes.

(With agency inputs)