The EU refugee deal with Turkey championed by Angela Merkel will be put under further strain on Thursday as the German parliament votes on a symbolic resolution on the Armenian genocide.

The five-page resolution, co-written by parliamentarians from the Christian Democrats, Social Democrats and Green party, calls for a “commemoration of the genocide of Armenian and other Christian minorities in the years 1915 and 1916”.

Turkish governments have always rejected the use of the term genocide to describe the massacre and expulsion of an estimated 1.5 million Armenians and members of Christian minorities in the Ottoman empire.

The UN defines genocide as any act “with intent to destroy, in whole or in part, a national, ethnical, racial or religious group, as such”.

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Turkey’s prime minister described the ballot as “a real test of the friendship” between his country and Germany. “Some nations that we consider friends, when they are experiencing trouble in domestic policy, attempt to divert attention from it,” Binali Yıldırım said at a meeting of his Justice and Development party on Thursday. “This resolution is an example of that.”

On Wednesday he had gone further, saying the ballot was “ridiculous” and arguing that the killings were an “ordinary” wartime event. Yıldırım repeated the warning from the Turkish president, Recep Tayyip Erdoğan, that bilateral ties would be damaged by Germany’s decision to call the massacre of Armenians by Ottoman forces a genocide.

“It’s a ridiculous vote,” Yıldırım said. “[This] was one of many ordinary events that can happen in any country, in any society under the conditions of world war one. We know that those who want Turkey to pay the bill for it do not have good intentions.”

He said historians, not politicians, should be the judges of what happened in 1915. He also underlined that the vote would upset the large Turkish community in Germany: “The 3.5 million Turks living in Germany are the biggest asset to our bilateral ties. I hope that the German parliament and decision-makers will not close their ears to the voices of 3.5 million voters.”

Facebook Twitter Pinterest The Turkish prime minister, Binali Yıldırım, said ties between his country and Germany could be damaged by the vote. Photograph: Katia Christodoulou/EPA

However, he added that a positive vote would not necessarily influence the EU-Turkey deal. “We are loyal to the agreements we have made. The EU should stand by its word in the same way. We are not a tribal state, we are the Turkish republic, a country with a deeply rooted tradition.”

On Tuesday, Erdoğan had warned German MPs that “if Germany is to be deceived by this, then bilateral diplomatic, economic, trade, political, and military ties – we are both Nato countries – will be damaged”.

An agreement between Turkey and the EU to return migrants arriving on the Greek islands to Turkey has in recent months reduced the number of refugees arriving in central Europe, easing pressure on Merkel, the German chancellor. But Erdoğan has since repeatedly questioned the conditions of the deal, with members of his party threatening to cancel the agreement altogether.

A letter, signed by more than 500 Turkish associations in Germany and sent to German lawmakers, argued that “over 90% of the Turkish population rightly rejects the accusation of genocide and considers it defamatory”, warning that passing the resolution would be “poison for the peaceful coexistence between Turks and Germans in this country, as well as in Turkey”.

Some historians argue that Germany, a close ally of the Ottoman empire during the first world war, was aware of the massacre at the time and supported it politically. The Bundestag’s resolution contains a passage acknowledging “the German Reich’s complicity in the events”, as well as six references to the Holocaust.

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Twenty governments, including those of France, Italy and Russia, have in the past described the mass killings of Armenians as a genocide, and Pope Francis referred to the killings as “the first genocide of the 20th century” in 2015. The German president, Joachim Gauck, also used the phrase in a speech in April last year.

Thursday’s vote was originally scheduled for last year, but was put on ice due to pressure from Germany’s governing coalition, reportedly for fear of destabilising Turkish-German relations. A revised draft of the resolution has been brought back to the Bundestag largely due to the efforts of the Green party’s Turkish-German co-chair Cem Özdemir.

Merkel will not be in the Bundestag for the vote because of other commitments, including a meeting with the Nato secretary general, Jens Stoltenberg.