The NSA affair became a German election issue on Thursday when Social Democrat candidate Peer Steinbrück accused Angela Merkel of "negligent" treatment of the issue. He said the revelations of US internet surveillance represented a "far-reaching interference with our basic democratic rights and personal self-determination", and that Merkel had failed to "protect German citizens' freedoms and interests".

His announcement followed a one-hour meeting with a group of writers and intellectuals who had signed an open letter to Merkel expressing their concern with her inaction over the NSA revelations. The letter, originally published in Frankfurter Allgemeine Zeitung in July, had since gathered 67,407 signatures.

On Wednesday, the group of writers, which includes novelist Juli Zeh (Dark Matter, The Method) and short story writer Ingo Schulze (Simple Stories), had organised a protest outside the chancellory, but were snubbed by the German leader.

Asked why he had decided to get involved in the protest, the writer and essayist Ralf Bönt said that "writers and essayists have an acute sense of the distinction between the private and the public word, which the government seems to pretend doesn't exist. I would have liked to walk into Angela Merkel's office and got her to sign a document saying I've got nothing to hide."

Novelist Priya Basil, a British citizen based in Berlin, expressed her regret that a similar debate hadn't sprung up among writers in the UK. She said: "Britain as a society has to invite writers to speak up, and be ready to listen and respond to what they say even if it's tough and disturbing."

In Germany, the protest by the self-billed "writers' delegation" was a throwback to the 1950s and 60s, when writers such as Günter Grass, Heinrich Böll and Hans-Magnus Enzensberger frequently spoke out on political issues such as engagement with the country's National Socialist past, nuclear power or the 1968 student protests. Grass has recently complained about the political apathy of Germany's next generation of intellectuals.