North Korea may be preparing a fourth nuclear test, according to officials in South Korea.
South Korea's unification minister Ryoo Kihl-jae told parliament there was an "indication" that Pyongyang was preparing for a fourth nuclear test.
His statement came after an unidentified South Korean official told the JoongAng Daily newspaper that signs of possible test preparations had been detected at Punggye-ri in North Korea, suggesting a fourth test could be imminent.
“There are recent active movements of manpower and vehicles at the southern tunnel at Punggye-ri," the “high-ranking” official said.
“We are monitoring because the situation is similar to behaviour seen prior to the third nuclear test.”
The official admitted it was not clear if the activities reflected genuine preparations for another nuclear test or were merely intended “to pressure Seoul and Washington.”
The rhetoric coming out of Pyongyang has been steadily escalating since North Korea carried out its third nuclear test on February 12, triggering international condemnation and increased sanctions from the United Nations.
Recent weeks have seen North Korean leaders step up their verbal offensive against the United States and South Korea with an almost daily barrage of threats now flowing out of the hermit nation.
In late March, the country’s state-controlled KCNA news agency vowed North Korea’s nuclear program would “never be abandoned as long as imperialists and nuclear weapons exist on earth”.
The report about a possible fourth test, followed a warning from Xi Jinping, the president of China, Pyongyang’s only major ally.
“No one should be allowed to throw a region and even the whole world into chaos for selfish gains,” Mr Xi told a conference on Sunday, in a clear but indirect reference to the current crisis unfolding in North Korea.
Reflecting growing Chinese frustration with North Korea’s leader, Kim Jong-un, Mr Xi said: “Stability in Asia now faces new challenges, as hotspot issues keep emerging.”
Governments should attempt to “foster a sense of community” rather than transforming the world into “an arena where gladiators fight each other,” Mr Xi added.
On Sunday, China’s foreign ministry said it was now “gravely concerned about the growing tensions on the Korean Peninsula.”
British foreign secretary William Hague warned of “the danger of miscalculation by the North Korean regime” during an interview with the BBC.
But Mr Hague urged calm. “We have not seen the repositioning of forces or the redeployment of ground forces that one might see in a period prior to a military assault or to an all-out conflict.”