A mosque and an international congress centre were attacked in two explosions in the city of Dresden, but nobody was injured, German police said.
Dresden police said in a statement on Tuesday the explosions took place late on Monday, and there was no immediate report on the extent of damage.
Police president Horst Kretschmar said: "Even though we do not have a letter of confession, we must assume there's a xenophobic background."
Police found pieces of a home-made explosive device in front of the congress centre. They also increased the security in front of mosques all over Dresden.
Dresden will hold Germany's national unification celebrations next Monday. It is the state capital of Saxony which has seen a lot of racist attacks recently.