The Korea Meteorological Administration initially put the scale of the natural disaster at magnitude 5.7. and said that the seismic wave was recorded at 12.36 p.m.
North Korea in July conducted its first ever ICBM tests, part of a stunning jump in progress for the country's nuclear and missile program since Kim rose to power following his father's death in late 2011. The announcement was made on state television, which also said no radiation had been released into the atmosphere.
"The scale of the energy was five to six times more powerful than the fifth nuclear test", Lee Mi-Sun, head of the Korea Meteorological Administration's quake and volcano centre, told a televised briefing.
South Korea will hold a National Security Council meeting Sunday to discuss the incident, according to South Korea's Presidential office.
North Korea appears to have conducted a sixth nuclear test, the South Korea's Yonhap News Agency says, just hours after Pyongyang claimed to have developed a powerful hydrogen bomb.
USA monitors measured a 6.3-magnitude "explosion" near the North's main testing site at Punggye-ri.
In a written statement, Macron "calls on the members of the United Nations Security Council to quickly react to this new violation by North Korea of worldwide law".
The Russian Foreign Ministry says North Korea's claim to have tested a hydrogen bomb "deserves the strongest condemnation".
Tensions between North Korea and the worldwide community flared against last week after Pyongyang flew a missile over Japan.
President Trump threatened to meet North Korea with "fire and fury" in response to North Korean threats.
South Korea's Joint Chiefs of Staff said the military has raised its alert status after detecting a "man-made quake near Punggye-ri".
North Korea claims it has again tested a hydrogen bomb underground and that it "successfully" loaded it onto the tip of an intercontinental ballistic missile, a claim that if true, crosses a "red line" drawn by South Korea's president last month.
China, North Korea's only real ally and worldwide patron, has yet to respond. North Korea has become increasingly cut off by other rounds of sanctions and therefore more effective in surviving off the books.
"If North Korea did indeed conduct a nuclear test, we absolutely can not tolerate and must protest firmly".
Japan Meteorological Agency also observed a magnitude-6.1 tremor in North Korea, which showed a different waveform from a natural quake around 12:31 p.m. local (11:31 p.m. ET).
Experts have said for months that another nuclear test was likely on the way, with satellite imagery revealing that a new tunnel had been dug earlier this year.
If confirmed as a nuclear test, this act would indicate that the DPRK's nuclear programme is advancing rapidly.
"China, North Korea's only real ally and patron, said its neighbor "disregarded universal opposition of the worldwide community" by conducting the test". It last detonated a nuclear device on 9 September-its foundation day-last year.
It flew a Hwasong-12 over northern Japan last week, the first such overflight by a missile capable of carrying nukes, in a launch Mr Kim described as a "meaningful prelude" to containing Guam, the home of major United States military facilities, and more ballistic missile tests targeting the Pacific.
A second, smaller tremor was detected by the USGS and its Chinese counterpart. Hours earlier, Pyongyang claimed its leader had inspected a hydrogen bomb meant for a new intercontinental ballistic missile.
The recent statement by North Korea comes at a time of increased regional tension in the wake of Pyongyang's recent missile tests in July, one of which was launched over Japan and the others having the potential to fly almost 10,000 km (6,200 miles) away, putting at risk several parts of the mainland United States.