Danish press has reported that that country’s secret service helped the US spy on European politicians, including German Chancellor Angela Merkel from 2012 to 2014, who is a close US ally.
The Danish Defence Intelligence Service (FE) collaborated with the US National Security Agency (NSA) to gather information, public-service broadcaster DR has reported.
Similar intelligence was gathered on officials from France, Sweden and Norway, the report says.
In 2013, US whistleblower Edward Snowden also alleged tapping of the German chancellor's phone by the NSA.
No denial was made by the White House, though spokesmen said Mrs Merkel's phone was not bugged at the time, and would not be in future.