German Army and border guards have also been put on full alert at all crossing points into the country.
"We have received concrete indications that Islamic terrorists are planning attacks by the end of this month. The attacks are to be similar to the Mumbai assaults by Pakistani militants two years ago", German Interior Minister Thomas de Maiziere has said.
Speaking at a function last night, the minister said the attacks could also be on smaller scale or carried out by individuals.
Known for his reluctance not to press the panic button, Maiziere said he was going ahead to issue full alert this time because the tip off that came from a friendly intelligence service was "very concrete".
He said German security and intelligence agencies had drawn up a list of possible targets and stepped up vigil countrywide. Maiziere said the public at large had also been asked to be vigilant.
The German security boost comes in the wake of media reports that a group of six people including four of Pakistani origin have sneaked into Europe on Schengen visas, which would allow them access to Germany also.
Meanwhile, a Berlin daily 'Tagesspiegel' reported that the US authorities had tipped-off Germans that a group of four Al Qaeda terrorists were on their way to carry out attacks in Germany and Britain.
They may sneak into Germany on November 22, according to the US informants.
The newspaper said the Pakistani Islamic militant Mohammed Ilyas Kashmiri is the mastermind behind the planned attacks.
Kashmiri reportedly plotted the attack on the "German Bakery" in Pune this February in which 17 persons were killed and around 60 injured, including a German.
He is reported to have recruited two to four persons in the border areas between Pakistan and Afghanistan and they have possibly left for Germany via India and the UAE, the newspaper said.
German Federal Crime Office is also trying to trace the whereabouts of a small group of people from Berlin, who suddenly disappeared after converting to Islam, the newspaper reported.