Armenians say they were victims of an ethnic-cleansing campaign planned by Turkish nationalists as the Ottoman Empire crumbled amid the first world war.
They say between 1915 and 1923 hundreds of thousands of Armenians were forcibly marched through the Mesopotamian desert where they died of dehydration and starvation.
Turkey denies this. It says thousands of Armenians and Turks died in a civil conflict that erupted after Armenians sided with invading Russian forces.
To this day, the historical events surrounding the killings remain hotly contested.
Many academics say the Armenian version of events holds water.
"Among most bona fide historians this is non-debate. Turkish nationalist historians still reject this," Donald Bloxham, a history lecturer at Edinburgh University, said.
Historian Bernard Lewis (R) has
backed Turkey's view of events
Bloxham, who has just completed a book entitled The Great Game of Genocide: Imperialism, Nationalism and the Destruction of the Ottoman Armenians, said: "The Turkish version just doesn't stand on any level."
On the other hand, there are several historians, such as Middle East scholar Bernard Lewis, whose works support the Turkish account of events.
"There is an explainable, understandable history of a two-sided conflict. It was not genocide," Justine McCarthy of the University of Louisville wrote in the Turkish Daily News in 2001.
However, there is increasing international and domestic pressure on Turkey to recognise the killings as a genocide, suggesting that, in this instance, history is not on Turkey's side.
Last week a record 32 US senators and more than 100 legislators wrote to US President George Bush asking him to recognise the genocide.
"The memory of the Armenian genocide underscores our responsibility to help convey our cherished tradition of respect for fundamental human rights and opposition to mass slaughters. It is in the best interests of our nation and the entire global community to remember the past," the senators wrote.
The Armenian lobby in the US is hoping Bush will use the word genocide in a speech commemorating the anniversary of the 1915 killings.
Armenians hope George Bush
will use the term 'genocide'
"The overall aim of the community is to get recognition of the genocide," Elizabeth Chouldijian of the Armenian National Committee of America said.
Whether Bush is willing to offend an important strategic ally in order to appease a relatively weak domestic lobby, remains to be seen. Turkey has traditionally been an important Nato ally and a key military partner with the US.
"The president speaks of moral clarity over international issues and we ask him to have moral clarity over this issue too," Chouldijian told Aljazeera.net.
Pressure on Turkey is also growing elsewere.
The Polish parliament and the Russian Duma have adopted resolutions that will call on the international community to recognise the genocide. In Germany, officials have said they will urge Turkey to acknowledge the incident as such.
In France, home to the largest Armenian community in Europe, French President Jacques Chirac accompanied Armenian President Robert Kocharian to a monument for victims of the killings in Paris on Friday.
France's Jacques Chirac visited a
memorial to the dead in Paris
In Belgium, the parliament voted on Saturday to make denying the Armenian genocide illegal.
In addition to international pressure, there are an increasing number of Turkish intellectuals and academics who are breaking a taboo and calling for the events to be recognised as genocide.
The Turkish writer Orhan Pamuk received death threats after he recently told a Swiss newspaper that "no one dares say that a million Armenians and 30,000 Kurds were killed in Turkey".
The issue has strong resonance in the foreign affairs of both Turkey and Armenia.
Relations between the two countries are tense. Ankara refuses to establish relations with Yerevan because of the genocide row and Turkey closed its border with Armenia in 1993 because of its war with Azerbaijan, depriving the tiny, landlocked country of a key trade route.
Armenia says that as long as Turkey fails to recognise the genocide, then it will feel threatened by its neighbour.
"Without recognition of the fact of genocide and an admission that it was wrong, we cannot trust our neighbour, which has a tangible military weight," Armenia's foreign minister, Vardan Oskanyan, said.
of the fact of genocide and an admission that
it was wrong, we cannot trust our neighbour, which has a tangible
Armenian Foreign Minister Vardan Oskanyan
Harry Tamrazian, head of the Armenian service at Radio Free Europe, said: "This is very important for Armenia. The very fact Ankara refuses to recognise the Armenian genocide is very disturbing for Armenian security."
Armenians say they want to seek compensation for the genocide, something that observers say unnerves Turkey.
"When any genocide is committed, it is a crime and there must be repercussions. Once the genocide is recognised, then the next step is looking into what the consequences are according to international law," Chouldijian of the Armenian National Committee of America says.
Crucial to EU talks
Tamrazian echoes Chouldijian.
"They are afraid of dealing with the consequences. Once you recognise the genocide, they think Armenians will ask for compensation," he told Aljazeera.net.
As Turkey prepares for EU accession talks, the Armenian genocide is something Ankara cannot avoid.
"There is a European moral standard that says if you want to be a member of the Western world, then you have to allow a discussion, a debate, of the past, and second you have to be ready to rectify the wrongdoings of the past," Turkish historian Taner Akcam said at a recent conference on the genocide in Armenia.
Turkey is a key US strategic
partner and Nato ally
Some EU members say Turkey must examine its past before it joins the bloc, something that irks Turkey.
To which Turkish President Ahmet Necdet Sezer responds: "It is wrong and unjust for our European friends to press Turkey on these issues.
"These claims upset and hurt the feelings of the Turkish nation. What needs to be done is research and investigate and discuss history, based on documents and without prejudice."
Turkey has offered to open its Ottoman archives to a joint commission of Turkish and Armenian historians to research the genocide issue, something that the Armenian government has dismissed, saying that incriminating documents have been removed.
The Armenian issue also raises questions over the nature of the Turkish state.
"The Armenian genocide issue is a living one," says Edinburgh University's Bloxham.
"Turkish ethnic nationalism was the ideology behind the genocide, it is this same ideology that has been behind its problems with the Kurdish population," he said.
"So to question this ideology and the genocide would also confront ethnic nationalism, and Turkey would then have to confront its relationship with the Kurds."
For their part, Turks say European countries are using the Armenian genocide issue to hinder Turkey's attempt to join the EU.
Pulent Akargly, an MP with the Turkish National Party, says: "Turkey will never accept genocide allegations just because European and American parliaments say so."
Akargly says Turkey has the strength to dismiss such demands.
Armenians in Yerevan observe
the anniversary of the events
"They can make pressure but this will not have any serious impact on Turkey. Because Turkey is a country of 70 million with a strong army and a strong market in a strategic area, I believe that more and more the EU and the US need Turkey more than we need them."
Akargly also accuses Europe and the US of gross hypocrisy, saying: "The Western world has to recognise genocide with what they have done in Latin America. Then what has been done during the Crusader period, then what has been done in black Africa and Arab Africa and during Vietnam."
But as Turkey undergoes EU-driven reform, many in the country say that challenging the nationalist historiography will become easier.
"I think we will hear different voices," Etyen Mahcupyan, a Turkish journalist of Armenian descent, recently told Radio Free Europe.
"We will see that at least part of the public thinks differently - very differently, in fact - from the state. We will then obligatorily see a discussion take place between state and society. This is, in fact, democratisation."