Germany has protested Russia's decision to turn away an ally of Chancellor Angela Merkel.
Conservative lawmaker Karl-Georg Wellmann was denied entry into Russia when he arrived at a Moscow airport on May 24, and returned to Germany on May 25.
Wellmann has been a vocal critic of Russia's actions in eastern Ukraine, where Russian-backed separatist rebels have been fighting government forces.
Germany's Foreign Ministry said in a statement on May 25 that the Russian government's decision was "incomprehensible and unacceptable," and called on Moscow to lift any entry ban against Wellmann.
The protest was delivered to the Russian government by Germany's ambassador in Moscow and to the Russian embassy in Berlin.
Based on reporting by AP and dpa