A leader of Germany's opposition Greens who has Turkish roots has received death threats after he pushed for a resolution approved last week by the German parliament that declares the 1915 massacre of Armenians by Ottoman Turkish forces a genocide.
Turkey recalled its ambassador to Germany in protest against the resolution. Ankara accepts that large numbers of Christian Armenians were killed on Ottoman territory during World War One but denies the killings amounted to a genocide.
Cem Oezdemir, one of the initiators of the resolution, has received death threats via Twitter, Facebook and email - some of them from Germans with Turkish roots in Germany and others from Turks in Turkey, said Julia Jorch, a spokeswoman for the Greens.
She said Oezdemir often received insults from right-wing extremists and Turkish nationalists and sometimes death threats but the number of these had surged in the run-up to and after the resolution, which parliament approved last Thursday.
On Monday Oezdemir was defiant, saying: "Votes in the German parliament are not dependent on which authoritarian ruler they make happy and which they don't."
On Sunday Erdogan lashed out at the German parliament for passing the resolution and suggested that Germany was being hypocritical given its own history.
"Look Germany, I am saying this again; first you will be held accountable for the Holocaust, then you will be held accountable on how you killed and destroyed more than 100,000 Namibians in Namibia," Erdogan said at the graduation ceremony of a university in Istanbul, according to comments published by the state-run Anadolu agency.
During Adolf Hitler's Third Reich six million Jews were murdered and in the early 1900s, when Namibia was a German colony, Germans carried out a campaign of slaughter there among the Herero and Nama tribes.
"You are the last country who could conduct a parliamentary vote for Turkey on the so-called Armenian genocide. We have no issues, no problem in our history on this topic. Our history is not one of massacres. Our history is one of compassion and mercy and that is our difference," Erdogan said.
Germany has long acknowledged its guilt for the Holocaust and other Nazi atrocities and began in 1952 to pay compensation to Israel. In 2012 Berlin said it would pay a lifelong monthly pension to Jews who spent time in concentration camps or ghettos or who survived the Nazi regime by living in hiding or under a false identity.
Germany is home to a large ethnic Turkish community and is also an important trade partner for Turkey.