North Korea used its embassy in Berlin to obtain technology secretly for its nuclear weapons programme, according to new disclosures from Germany's domestic intelligence service.
Repeated moves by the embassy to buy equipment that could be used for ballistic missiles and nuclear weapons were uncovered over the past two years, according to The Daily Telegraph UK.
"We discovered procurement activities taking place there, which we believe were focused on the missile program, and also to some extent on the nuclear program," said Hans-Georg Maassen, the head of the Bundesamt für Verfassungsschutz (BfV), or Office for the Protection of the Constitution.
"When we detect something of this sort, we take steps to prevent it," Mr Maassen told German television. "But we can't guarantee that we are able to detect and prevent every case."
The disclosures were made by Mr Maassen in an interview with NDR television for a report that is to be aired in full on Monday.
In brief extracts released in advance, the intelligence chief described how the North Korean embassy had purchased "dual use" technology that could be employed for civilian or military purposes.
"They were acquired in other markets or front companies were used to buy them in Germany," he said.
Mr Maassen did not specify what material the embassy was attempting to purchase for its nuclear or missile programmes.
But in a separate incident in 2014 a North Korean diplomat is believed to have tried to obtain a multi-gas monitor that could be used to develop chemical weapons.
Along with the UK, Germany is one of a handful of European countries to maintain diplomatic relations with North Korea.
It withdrew several of its diplomats from its embassy in Pyongyang in the wake of last year's missile tests, and has demanded North Korea reduce its diplomatic staff in Berlin.
The German foreign ministry denied reports it was coming under US pressure to close its embassy and cut diplomatic ties altogether last year. But a spokesman added: "That doesn't mean we're ruling it out."
Berlin's slightly less frosty relations with Pyonyang than most Western governments date back to the Cold War, when communist East Germany viewed North Korea as an ally.
Angela Merkel's government at one point hoped it could exploit that shared past to serve as a bridge with the regime of Kim Jong Un. But little has materialised, and the latest disclosures are unlikely to raise expectations.
They come after a United Nations report found North Korea raised nearly $200m (NZ$274m) in revenue by flouting international sanctions last year.
Pyongyang continued to export coal, iron, steel and other banned commodities in defiance of the sanctions, according to the report.
It came as sources close to Mike Pence, the US president, said he would brand the North's efforts to portray itself in a positive light at the Winter Olympics in South Korea as a "charade."
"The Vice President will remind the world that everything the North Koreans do at the Olympics is a charade to cover up the fact that they are the most tyrannical and oppressive regime on the planet," said an aide to Mr Pence, who will lead the US delegation to the Olympics.
"At every opportunity, the V.P. will point out the reality of the oppression in North Korea by a regime that has enslaved its people. We will not allow North Korea's propaganda to hijack the messaging of the Olympics," the aide added.
Meanwhile, China said on Sunday that it firmly opposed US plans to diversify its nuclear armoury with smaller bombs, likening its approach to the Cold War.