"If China completely cuts off the supply of oil to North Korea or even closes the China-North Korea border, it is uncertain whether we can deter Pyongyang from conducting further nuclear tests and missile launches", it said.
Los Angeles Times reported in 1998, "Clinton has just pulled out of his pocket for North Korea", and he "decided to spend as much as $15 million for North Korean fuel oil, beyond the $35 million already authorized by Congress this year".
An official from Seoul's meteorological agency said it had been detected near where North Korea had recently conducted a nuclear test, but said it was clear the quake was not caused by an artificial explosion.
Refined oil exports to North Korea from all United Nations members is capped at 500,000 barrels from October 1 to the end of the year and 2 million barrels annually from January 1, 2018.
This undated picture released by North Korea's official Korean Central News Agency (KCNA) on 28 May, 2017, shows North Korean leader Kim Jong-Un (C) inspecting the test of a new anti-aircraft guided weapon system organised by the Academy of National Defence Science at an undisclosed location.
A spokesman for South Korea's presidential Blue House said institutions analysing the seismic activity maintain that "it was natural and not from explosion".
A 3.5-magnitude quake was detected in northern North Korea on Saturday afternoon, near the nation's known nuclear test site, according to the U.S. Geological Survey.
This week marked a new level of acromony in a blistering war of words between Kim and Trump, with the North Korean leader calling the American president "mentally deranged" and a "dotard".
"A key method is to look at the seismic waves or seismic acoustic waves and the latter can be detected in the case of a man-made quake", said the South Korean official, who asked for anonymity.
North Korea's foreign minister, Ri Yong Ho, said Thursday that the country could soon test a hydrogen bomb over the Pacific Ocean.
But its magnitude was lower than those of quakes triggered by previous nuclear tests.
"A likely explanation of the signals is an aftershock or rock failure resulting from the previous large underground nuclear test carried out on September 3, the agency said".
There was no immediate reaction from China's Foreign Ministry, but the news was widely reported by Chinese state media outlets and on social media. Satellite photos of the area after the September 3 quake showed numerous landslides apparently caused by the massive blast, which North Korea said was an advanced hydrogen bomb.
Donald Trump later used his speech to the UN General Assembly to tell the world he would "totally destroy" North Korea if the U.S. was threatened by its regime.
Earlier on Saturday, China said it will limit exports of refined petroleum products from October 1 and ban exports of condensates and liquefied natural gas immediately to comply with the latest United Nations sanctions. On Thursday, the USA unveiled its own set of economic sanctions targeting North Korea.