Turkey has recalled the German ambassador after the country's parliament approved a motion to recognise the mass killings of Armenians between 1915 and 1917 as a "genocide".
Both the Armenian government and many historians have said that around 1.5m Armenians were forced to march through the Syrian desert by the ruling Ottoman Turks as their empire disintergrated at the end of the First World War.
Ankara has insisted that this is an exagerration and that 300,000 people on both sides of conflict were killed in fighting during the civil war.
Modern Turkey was proclaimed in 1920 by Kemal Ataturk and its former territories were either put under the control of the Allied powers or granted independence following the end of the war.
Germany has joined more than 20 nations, including France and Russia, in recognising the massacre as a genocide.
International figures such as Pope Francis and organisations like the European Union have also publicly recognised it.
The move comes at a time when the EU is relying on Turkey to readmit refugees who are fleeing conflict in Iraq and Syria.
Under a deal approved early this year, Turkey and EU member states who swap refugees already in the camps for those who had attempt the Mediterrenean crossing in a "one-for-one" exchange.
The terms of the agreement also mean Turkey will receive aid and visa-free travel for its citizens if certain pre-conditions are met.
Following the deal German Chancellor Angela Merkel was accused of pandering to Turkish President Recep Tayyip Erdogan after she allowed a German comedian to be prosecuted for writing an obscene poem about his under an arcane law which forbids insulting foreign heads of state.
Ms Merkel was not in the Bundestag for the vote but her Christian Democrat party (CDU) overwhelmingly backed the resolution, the BBC reports.
MPs came under pressure from Turkish authorities in the run-up to the vote with some receiving threatening and abusive emails, German media reports.
Mr Erdogan is said to have personally phone Ms Merkel to warn her that ties between the two countries would suffer as a result of the vote going through.
The headline and text of the bill explicitly refers to the "genocide" of the Armenian people - but also takes the step of accepting partial blame as Germany was an ally of the Ottomans at the time and did nothing to stop the killings.
A joint statement by members of the Turkish Grand National Assembly and from leading Turkish political parties - including the ruling AFK party - released to The Independent said: "We strongly condemn and reject this bill falsifying historical facts about 1915 events and not complying with the law.
"It is utterly unacceptable that the events, which took place under the special conditions of World War One 101 years ago and caused heartbreaking suffering for both Turks and Armenians, be introduced as “genocide” based on biased, distorted and various subjective political motives.
"This bill constitutes one of the worst examples of how the above-cited events are politicized and exploited in our day; and it is not possible to give credit to Germany’s ridiculous justification that the bill will pave the way for Germany’s 'assuming its special historical responsibility' and 'supporting Turks and Armenians in bridging the gaps of the past while searching for ways for reconciliation and settlement'."
