Germany's diplomatic missions in Turkey were closed Thursday due to "very concrete" indications of planned terrorist attacks, Foreign Minister Frank-Walter Steinmeier said in Berlin.
The German embassy in the capital Ankara, the consulate general in Istanbul, as well as German schools in both cities, were closed on Thursday, four days after a bombing in the Turkish capital in which 37 people were killed.
"Last night our security services received several very concrete and very serious indications that terrorist attacks against our diplomatic missions in Turkey had been planned," Steinmeier said.
"This was a necessary measure to ensure the protection of German citizens and those working and learning in these institutions, which has to take precedence now," he added.
The German consulate in Istanbul announced the move in an email, saying the decision had been made after a tip-off that was "not conclusively verifiable" and that the facilities would remain shut throughout the day as a precaution.
Steinmeier said that security would be ramped up at the facilities and that a committee has been tasked with gathering information about the security situation in Turkey.
The local government in Istanbul sharply criticized the move, arguing it will "negatively influence" the public, according to the DHA news agency.
The measures are based on "unverified intelligence" and were carried out without consulting Turkish authorities, the agency reported citing a statement from the governorship.
Germany's Foreign Ministry issued a statement on its website urging anyone in Istanbul, Ankara or other major cities in Turkey to be on high alert.
The warning advised against congregating in large groups in public spaces, visiting tourist attractions and spending time in areas near government or military facilities.
At least 37 people were killed in a car bombing in Ankara on Sunday, which was claimed by the hardline Kurdistan Freedom Falcons (TAK).
TAK is a splinter group of the banned Kurdistan Workers' Party (PKK), with whom Turkey has fought a bloody war since a two-year ceasefire broke down in July 2015.
In January, 12 German tourists were killed in a suicide attack in central Istanbul blamed on the Islamic State militant group.