A bill to be voted in German parliament later this week that declares the 1915 killings of Armenians during the Ottoman rule as genocide raises fresh concerns over a key migrant deal between Turkey and the EU, as Ankara warns of consequences.

Turkey’s President Recep Tayyip Erdogan raised the issue with German Chancellor Angela Merkel in a telephone conversation. The bill would damage bilateral economic, political and military relations, Erdogan told Merkel. The timing of the bill, drawn up by the ruling left-right coalition and the opposition Greens, couldn’t have been worse for Merkel, who has been struggling to keep the migrant agreement with Turkey alive. If passed, the resolution may restrain relations between Berlin and Ankara and may even put the implementation of the refugee accord at risk.

Merkel claims that the migrant deal is working and beneficial. “The Turkey agreement is a model of the balancing out of our interests," Merkel told a party meeting of her European EPP group earlier this week, AP reported. But it has become more difficult for European politicians to deal with Turkey since the stepping down of Ahmet Davutoglu, one of the architects of the EU-Turkey agreement, as prime minister last month. Erdogan is more sceptical than Davutoglu towards the EU and the migrant agreement, threatening to abandon the accord if the EU fails to grant Turks visa-free travel to the Schengen area. But, Germany’s Foreign Minister Frank-Walter Steinmeier thinks Turkey would not use the proposed genocide bill to cancel the migrant agreement.

The resolution may also provoke some 3 million Turks living in Germany.

Turkey acknowledges that Armenians were killed during the first world war but it says that the mass deaths were part of a conflict and Turks were also killed. Armenians argue that up to 1.5mn Armenians were killed in 1915. Turkey has always disputed this figure and it claims that the killings of Armenians did not amount to genocide.