According to a report published by the Telegraph on Wednesday, the incident occurred in the town of Parchim in the German state of Mecklenburg-Vorpommern on August 26.
For some time, Muslims, who had come there for Friday Prayers, were barred by the vandals from entering the mosque.
The hastily-erected wall, covered by flyers attached to it such as “You call yourself believers, we call you invaders,” shocked the small Muslim community in the small town of 19,000 residents.
The mosque has no minarets, and no call to prayer is broadcast on Fridays for some 150 Muslims living there.
Friday’s incident is said to be the second such attack against the small town’s mosque during the past few months.
An investigation is underway into both incidents, but anti-Islam and anti-refugee elements are suspected to have been behind the hate attack.
Over the past months, Germany has witnessed a rise in hate crimes against refugees and Muslims following Merkel’s open-door policy regarding the asylum seekers arriving in the country mainly from violence-torn states in the Middle East and Africa.
Since the beginning of this year, refugee shelters across Germany have reportedly come under 650 xenophobic attacks.
On Sunday, Merkel, in an interview with the German public television channel ARD, reiterated her previous stance on accepting Muslim refugees, saying “What I continue to think is wrong is that some say ‘we generally don’t want Muslims in our country, regardless of whether there’s a humanitarian need or not.’”
Muslims make up nearly five percent of the total population of Germany, which is home to some four million Muslims.
Europe is facing its worst refugee crisis since the end of World War II.
Many blame major European powers for the unprecedented exodus, saying their policies have led to a surge in terrorism and war in the violence-hit regions, forcing more people out of their homes.