North Korea has begun testing a nuclear reactor that could be used to produce weapons-grade plutonium, according to intelligence analysts.
The country has been developing an experimental light water reactor at the Yongbyon Atomic Energy Research Centre for several years, but activity is said to have increased in recent months.
Experts say recent satellite imagery shows the reactor has been structurally finished and there is evidence testing has begun.
According to a report by intelligence analysts Jane’s Intelligence Review, the imagery showed emissions on non-condensable gases from a stack at the reactor.
Although the reactor could be used to produce weapons-grade plutonium, North Korea is believed to already have enough fissile material for several nuclear bombs.
Construction of the experimental light water reactor was completed in 2013 and it was optimised for civilian electricity production, but is not operational.
Joshua Pollack, a senior research associate at the Middlebury Institute of International Studies at Monterey, said the reactor is likely to be too small to provide much electricity.
He said it was part of an effort to develop a light water reactor after a deal to provide nuclear power reactors by an international consortium, including the US, broke down in 1990.
Mr Pollack said: “It’s their way of saying, ‘see, since you won’t give us what you promised, we’ll do it ourselves’. They haven’t made any agreements lately with the US so the work goes on.
It comes as South Korea officials were set to convene for their first meeting to prepare for a summit between President Moon Jae-in and North Korea leader Kim Jong Un in April.
US President Donald Trump has also accepted an invitation from Mr Kim after a South Korean envoy told him the North’s leader was prepared to discuss denuclearisation.
The White House said the meeting would take place by May, although a venue has yet to be decided.
North Korea’s foreign minister Ri Yong Ho travelled to Sweden on Friday, leading to speculation the Trump-Kim talks will take place in the country, or that Sweden is helping to set up the summit elsewhere.