Germany summoned the Belarusian ambassador on September 20 after Minsk denied visas to two European election observers who were planning to monitor the upcoming parliamentary elections in Belarus.
The German Foreign Ministry told Ambassador Andrei Giro that visa denials, as well as press restrictions ahead of the September 23 vote, send a "negative signal."
On September 19, the Organization for Security and Cooperation in Europe announced two of its representatives -- members of the Parliamentary Assembly of the Council of Europe from Germany and Lithuania -- have been denied entry visas to Belarus to work as election monitors.
The OSCE said Belarus did not provide any explanation for the visa denials.
The vote is expected to elect a rubber-stamp parliament, with most powers remaining in the hands of authoritarian President Alyaksandr Lukashenka.
Two major opposition parties have announced they will boycott the vote.
German Foreign Minister Guido Westerwelle told a news conference in Berlin that the move by Belarus shows the importance of European involvement for the preservation of human rights in neighboring countries.
"I deeply regret this. It shows how important our European involvement is for the preservation of human rights in our neighboring European countries. I have summoned the Belarusian ambassador to the Foreign Ministry and we will make our position very clear one more time," Westerwelle said.
Maja Kocijancic, a spokeswoman for EU foreign policy chief Catherine Ashton, told RFE/RL the European Union regrets Minsk's decision and expects the Belarusian authorities to enable election monitors to do their job.
"Two observers were not allowed to enter Belarus to observe the elections, which is something we regret," Kocijancic said.
"The election observation mission of the OSCE is in Belarus on the invitation of the Belarusian authorities and we expect the Belarusian authorities to enable them to do their job."
The OSCE has fielded more than 300 observers to monitor the elections.
President Lukashenka has ruled Belarus since 1994, cracking down on dissent and independent media.
The country has become increasingly isolated since a crackdown on dissent after the 2010 presidential election results were announced. According to those official election results, Lukashenka won a fourth term.
With reporting by AP and AFP