Covering a period from 2012 to 2014, during the Obama administration, the NSA used Danish information cables to spy on officials in France, Germany, Sweden and Norway, according to a 2015 internal Danish Defence Intelligence investigation. DR cited nine sources who had access to that investigation.
Denmark and the US are close allies.
The allegations into spying is extremely serious, said Clément Beaune, the French Secretary of State for European Affairs.
"We must verify whether our partners within the Union, the Danes, have made mistakes in their cooperation with the American services," said Beaune.
Others who were allegedly targeted included German Chancellor Angela Merkel, German Foreign Minister Frank-Walter Steinmeier and former German opposition leader Peer Steinbrück.
The German chancellery only found out about the allegations after questions by journalists, while Danish Defence Minister Trine Bramsen said she would not comment on “speculation,” but said that systematic wiretapping of allies is unacceptable.
"Politically I consider it a scandal," opposition leader Steinbrück told German broadcaster ARD.
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The Danish Defence Intelligence Service, the BSA and Washington’s Office of the Director of National Intelligence (DNI) declined to comment.
Connection to Edward Snowden
Denmark is host to a number of key landing stations for subsea internet cables to and from Sweden, Norway, Germany, Holland and Britain.
NSA intercepted calls, texts and chat messages to and from telephones of officials of the neighbouring countries, according to the sources who spoke to DR.
The Danish Defence Intelligence Service conducted a probe in 2014 after former NSA employee Edward Snowden leaked papers that revealed how NSA works, according to DR.
Snowden fled the US after leaking secret NSA files in 2013 and was given asylum in Russia.
