German leader Angela Merkel is coming under increasing pressure to act on the NSA spying scandal after it was revealed Washington spooks eavesdropped on the country's top news magazine as well as politicians.

Der Spiegel, a publication which enjoys a high level of trust among readers, politicians and the media classes in Europe, fell victim to the surveillance unleashed on Mrs Merkel and her top lieutenants.

The magazine said on Friday it learned through the Wikileaks platform that, four years ago, the CIA head - and NSA chief - in Berlin met with senior German politicians and 'urged' them to take action against a lawmaker accused of leaking intelligence information to Spiegel journalists.

Pressure: German leader Angela Merkel (left) is coming under increasing pressure to act after it was revealed that America's National Security Agency spied on the country's top news magazine

The alleged informant, Hans-Josef Vorbeck, later found himself shuffling paper in an archive instead of dealing with sensitive material - a move widely seen as Berlin bowing to Washington's wishes.

Germany, which has cherished a free press ever since the overthrow of Nazism, is more bitter about the Spiegel row than the surveillance of top politicians.

One German journalist told Radio Bavaria: 'This is a scandalous assault on a free press, a scandalous assault on the dignity of journalists and their craft. America perpetually claims it is acting in the interests of free people everywhere, but when you learn of dirty tricks like this, one must question this.'

For its part, Der Spiegel said the information gleaned from private conversations can only have come from the NSA. It said on Friday: 'It is becoming increasingly clear that representatives of the German government at best looked away as America violated the law, at worst supported them.'

Other media noted that Spiegel could be seen as a legitimate target by intelligence operatives as it has in the past published many stories about the NSA spying operation which has frustrated and annoyed Washington.

The media revelations came after it was announced by the whistleblower platform that Mrs Merkel, her economics minister and the finance minister were allegedly bugged in a long-running programme stretching back to the 1990's.

Spying: Other media noted that Spiegel could be seen as a legitimate target by intelligence operatives as it has in the past published many stories about the NSA (pictured, headquarters) spying

Mrs Merkel, who smoothed over relations with America after revelations last year that her own mobile phone was hacked by the agency, is now facing fresh demands for concrete action against Washington following the scandal which broke on Thursday.

She has so far made no public comment although Washington's ambassador to Berlin was summoned to the Chancellery where sources said Mrs Merkel's displeasure was made known to him 'in no uncertain terms.'

The rival Green Party claimed she has 'failed to restore faith' in the partnership with the USA.

'These things lead to an ever-greater mistrust among the public,' said Konstantin von Notz, a German parliament MP sitting on the NSA inquiry committee.

'That isn't good for the transatlantic relationship in these difficult times. Both the US and Frau Merkel come off badly.'

Part of the debate taking place within Germany centres on the role played by its own foreign intelligence service, the BND, and its levels of cooperation with the NSA.

Conservative elements in government have played down the spying allegations in the past, but the latest raft of revelations may prove too large to sweep under the diplomatic carpet.

Von Notz told a German news website: 'There are legal problems with what the BND has done, there have to be reforms and consequences. This couldn't-care-less attitude doesn't help our country or our intelligence services.

Diplomatic: Mrs Merkel (right) has smoothed over relations with America (President Barack Obama, left) after revelations last year that her own mobile phone was hacked by the NSA

'The USA and Germany and Europe are bound together by common values, including the rule of law. We have to reinstate the integrity of our relationship.'

Christian Flisek, the senior SPD lawmaker on the NSA committee, said the fresh revelations of spying were only the tip of the iceberg.

Finance Minister Wolfgang Schäuble took time out from trying to save the euro on Friday to say: 'The impression is forcing itself upon us that someone or other in the American secret services has somewhat lost sight of the norm.'

But he added spying by the Americans was a 'small problem', and that 'other world powers cause me more worry.'

Martina Renner from thje hard-left Die Linke party said: 'The government has wasted time debating whether the NSA also conducts espionage in Germany and offered only a vague response to repeated spying scandals.'

'All the assurances that Germany wasn't being spied on were apparently false,' said André Hahn, chairman of the Bundestag's intelligence oversight committee.