German Interior Minister Thomas de Maiziere told a news conference a series of incidents had led to the decision to increase security.
He said the tip came from the country's foreign partners, but investigations have also found information about continued efforts by extremist groups to attack Germany, including evidence that an apparent terror plot has been planned for the end of November.
At the end of last month, a mail bomb passed through Germany that was sent from Yemen and addressed to the United States. The bomb was intercepted in Britain. Earlier in October, intelligence agencies warned of a terror plot to launch attacks in Britain, France and Germany.
De Maiziere said there will now be an increased police presence at railway stations and airports, but said Germans should remain calm. He said there is reason for worry, but not for hysteria.
The security research group Maplecroft recently published its global Terrorism Risk Index, which rated Germany at "low risk" of a terror attack.
Maplecroft security analyst Anthony Skinner said that is because Germany has rarely been hit by terror attacks in the past year. But he said the threat level appears to be rising.
"Germany obviously is a member of NATO, it is a key ally of the West, of the U.K., of the United States and I think it has always remained in the crosshairs of al-Qaida," said Skinner.
He said when terror plots are thwarted security advisors often raise threat levels, but that uncovering a plot can mean security loopholes are filled.
"One might argue actually that even though the perception of risk has increased that it may, in fact, effectively diminish somewhat because the security services are even more on the ball," Skinner said.
De Maiziere said the current risk level is equal to what it was before last year's national elections.
Germany Heightens Security Over Terror Threat
