When German Chancellor Angela Merkel discovered that US intelligence agencies had bugged her phone in 2013, she famously told President Barack Obama that "spying between friends is not done."

Four years after Merkel's declaration, it has emerged that Germany's foreign intelligence agency, BND, spied on the White House and American companies for years, according to a report seen by German newspaper Der Spiegel.

The report states that just under 4,000 search terms were directed against American targets between 1998 and 2006.

The BND used these terms to surveil the telephone and fax numbers of staff at the White House and US Treasury. Other targets included the US Air Force, the Marine Corps, defence contractor Lockheed Martin and space agency Nasa.

German spies also accessed information from more than 100 embassies in Washington DC, according to newspaper Die Zeit.

The document also revealed the existence of anti-terror alliance between Western countries including the US, Germany and France.

In February, it was revealed that the BND was spying on journalists around the globe, including reporters at the BBC, Reuters and the New York Times.

The BND did not comment on its surveillance operations, but the agency's president, Bruno Kahl, did suggest that in future there would be stricter oversight: "The question of who the BND is permitted to surveil, and who it cannot, will not only be the subject of a stricter approval process in the future, but also more ambitious controls."

Earlier this year, Merkel told a parliamentary committee reviewing the actions of US intelligence agencies in Germany that she did not know about any BND operations in the US.

In 2013, the German chancellor expressed outrage when it emerged that America's National Security Agency (NSA) was monitoring her mobile phone as part of worldwide wiretapping operations.

Merkel Obama
German Chancellor Angela Merkel told Barack Obama in 2013 that "spying between friends, that's not done"BRENDAN SMIALOWSKI/AFP/Getty Images