Eleven German lawmakers of Turkish origin have received threats after they voted for a resolution that declared the 1915 massacre of Armenians by Ottoman forces a genocide, media reports said Saturday. Tensions between Berlin and Ankara escalated after the German parliament's decision earlier this month. 

After the threats, the German foreign ministry warned MPs of Turkish origin against travel to Turkey, saying that their security could not be guaranteed. The leader of Germany's Green party, Cem Oezdemir, who pushed for the resolution, also received death threats. Local media reported that the MPs under threat will receive security measures for both their professional and private activities.

"The threats against lawmakers of Turkish origin are unacceptable," Interior Minister Thomas de Maiziere told Frankfurt Allgemeine Sonntagszeitung. "Of course security measures will be adjusted if necessary."

He also stated that the majority of the 3.5 million people with Turkish roots who live in Germany were "good neighbors."

The 11 MPs face major backlash in Turkey for supporting the move. Turkish President Tayyip Erdogan reportedly said that the lawmakers, of Turkish origin, should undergo blood tests, accusing them of having "tainted blood" and of being terrorists.

Ankara's Mayor Melih Gökçek shared photos of the 11 MPs in a tweet, saying they "stabbed us in the back."

Armenians have claimed that up to 1.5 million of their people died in the atrocities of 1915, during the Ottoman Empire's collapse in World War I. However, Turkey has put the death toll much lower, rejecting the term "genocide."