Denmark’s intelligence service co-operated with the US's National Security Agency to spy on top-ranking European political allies, it was reported on Monday.
Communications from leaders such as Germany’s Chancellor Angela Merkel were intercepted by the Danish Defence Intelligence Service (FE) and passed on to the powerful NSA for several years.
Analysts from Denmark's Forsvarets Efterretningstjeneste secretly broke into undersea internet cables to listen to phone calls and read text messages from allies.
An investigation by several European media outlets including Danmark Radio (DR) also found that the two countries collaborated to spy on officials from Sweden, Norway and France.
The then German foreign minister Frank-Walter Steinmeier, and opposition leader Peer Steinbrück, were among the politicians whose phone numbers were bugged.
The allegations emerged after an internal classified report on FE’s role in the surveillance partnership agreement with the NSA between 2012 and 2014 was leaked to the media.
It also claimed that a special data centre was built to store the information at a Danish intelligence facility on the island of Amager, near Copenhagen.
The case, potentially the biggest intelligence scandal in Danish history, will raise issues of trust for the countries, most of which are members of both Nato and the European Union.
There was growing European anger and condemnation at the disclosures on Monday, with the German government saying that it would be in contact with the US and Denmark to demand an explanation.
"The federal government has taken note of the report and is in contact with all relevant national and international bodies for clarification," a government spokesman said. "As a matter of principle, and you already know this, I would ask you to understand that the federal government does not openly comment on matters concerning intelligence activities."
Sweden’s defence minister added to the condemnation of the two countries. “We want all the cards on the table," said Peter Hulqvist, adding it was “unacceptable to eavesdrop on allies.”
In Denmark, Karsten Hoenge, of the Socialist People’s Party, that supports Denmark’s Social Democratic government, said he would demand answers in parliament from the defence and justice ministers about the eavesdropping, which was codenamed Operation Dunhammer.
“The government must explain how Denmark has been acting as a willing tool for a US intelligence service, and what it will mean for co-operation with Denmark’s neighbouring countries,” he said.
Trine Bramsen, the Danish defence minister since 2019, was reportedly informed of the espionage in August last year. She told DR that “systematic eavesdropping of close allies” was “clearly unacceptable”.
“This is a deep, serious and disturbing breach of trust if the NSA spied on Norwegian politicians through Denmark,” said Audun Lysbakken, the leader of Norway’s Socialist Left Party.
Clément Beaune, France’s Europe minister, described the reports as “extremely serious” if proven. “We need to see if our partners in the EU, the Danes, have committed errors in their co-operation with American services,” he told French radio. “Between allies, there must be trust, a minimal co-operation.”
The undersea cable spy system, described as the FE’s “crown jewel”, has mainly been used to gain intelligence on terrorist plots and information on Russia and China. Denmark acts as a hub for underwater internet cables, providing metadata that passes across the Baltic Sea into Scandinavia, mainland Europe and Russia.
The NSA’s tapping of Ms Merkel’s phone was first reported in 2013 when the American whistleblower Edward Snowden leaked a vast amount of information on the agency’s spying methods.
In the wake of the Snowden reports, former US president Barack Obama committed to stop spying on allies.
