According to the German news magazine Der Spiegel, Islamic extremists are planning an attack on the German parliament building, the Reichstag.
The reports suggest that al Qaeda and associated Islamist groups are planning to take hostages and fire at people in the building, which is both the seat of parliament and a popular tourist destination in Berlin.
The information reportedly comes from a jihadist who contacted the German authorities. Der Spiegel said the informant has repeatedly telephoned the German police from a foreign location in recent days, and is part of a terrorist cell of six people.
Two members of the cell are said to have been in Berlin for six to eight weeks and the attacks are reportedly planned for February or March 2011.
The magazine did not name its source.
Boosted security presence
Der Spiegel claims it is on the basis of this source's information that the Interior Minister Thomas de Maiziere warned earlier in the week that Islamists had planned attacks in Germany.
Security was increased at airports and train stations across Germany on Wednesday, when de Maiziere said there were "concrete" indications that militants were planning attacks.
He added there was "reason for concern, but not for hysteria."
Chancellor appeals for caution
German Chancellor Angela Merkel on Saturday told citizens not to be intimidated by the latest reported terrorist threats.
"We want to live freely and without fear in Germany - no terrorist threat will prevent us from doing so," Merkel told Bild am Sonntag newspaper.
"The security forces are doing everything possible to protect us," the chancellor added.
Speaking on the sidelines of the NATO summit in Lisbon, Merkel warned about possible terrorist attacks in Germany.
"There is a real danger of terrorism," said Merkel.
But the German chancellor refused to comment or confirm reports that suspected Islamist gunmen were planning an attack on the Reichstag building, telling journalists in the Portuguese capital she did not want to comment on "details."
At the same time the Christian Democrat politician said people should not "panic", stressing that the German security forces were working "attentively and appropriately" to the current situation.
According to Germany's police the danger of an Islamist terrorist attack in Germany has never been more specific. The head of Germany’s police force, Matthias Seeger, told the Frankfurter Allgemeinen Sonntagszeitung newspaper that there have been a number of tip offs from different sources.
On Tuesday a parliamentary committee will be holding a special session to discuss the current threat level, said CSU lawmaker Stefan Mueller in an interview with the German news agency dpa.
Mueller told journalists that Germany's anti-terror laws did not have to be tightened because of the current terrorist threats, but security forces have to be better equipped and more funds should be made available for more personnel for the police and intelligence service.
Author: Catherine Bolsover, Nigel Tandy (dpa, AP)
Editor: Martin Kuebler