YEREVAN, Armenia - On a rocky plateau overlooking the Armenian capital Yerevan, a small group of serious-faced teenagers each clutching a white flower stand under towering basalt stone slabs.

Their eyes are fixed on a flickering flame in the centre of a circular stone basin sunk in the rock before them.

Then, four move forward, slowly and deliberately but with no hint of the military precision normal at such sites, to lay their blossoms around the rim of the wide basin.

They take up position around the flame, trying to stare ahead but clearly embarrassed by the attention of visiting tourists.

"These are just kids, but they know what this is all about. Most of them will have heard family stories about the horror of those days and will know how important it is to remember," says Armen Baghdasaryan, a university teacher. "That's what this is about, remembering."

The scene is Armenia's "Genocide Memorial" at Tsitsernakaberd, Swallow Castle in the country's ancient Indo-European language, where above the rounded complex housing the flame a 44-metre (144 foot) steel stele, visible for miles around, soars into the sky.

This year the landlocked former Soviet state - surrounded by Turkey, Iran, Georgia and Azerbaijan - is marking the 100^th anniversary of the start of the events that remain embedded in the memories of Armenians.

The Armenians and independent historians say they brought the deaths between 1915 and 1923 of 1.5 million of the some two million Christian Armenian civilians who then lived in the largely Muslim Ottoman Empire.

On April 24, 1915 the then nationalist government of Turkey was already engaged in World War 1 on the side of Germany and Austria and feeling threatened by Tsarist Russia from the north.

Turkey ordered the arrest and execution of thousands of Armenian intellectuals and professional people in Istanbul and other major cities where many played prominent roles in Ottoman society.

The action was followed by the deportation in human columns of hundreds of thousands more Armenians from villages, towns and cities across eastern Turkey where they had lived for centuries.

Foreign diplomats, missionaries and even German officers who witnessed what happened as the columns of men, women, and children were marched westwards across scorching terrain into the deserts of Syria. They recounted scenes of mass starvation, rape and murder at the hands of escorting Turkish troops.

ARMENIAN KINGDOM OF CILICIA

Of the survivors, many dispersed around the eastern Mediterranean – where from the 11^th to the 13^th centuries an Armenian "Kingdom of Cilicia" had flourished – and others joined long-established communities in Europe and North America.

Many more moved north to the plains and valleys beyond Mount Ararat where Armenians – although in smaller numbers than in the Ottoman lands to the south-west.

There they had also lived for more than two millennia and by the early 19^th century had become subjects of the Russian Empire.

In today's Republic of Armenia, which emerged from the breakup of the Soviet Union in 1991 and now has a population of just over 3 million, officials and ordinary people insist that remembering the mass tragedy is not aimed at encouraging hatred towards Turks and Turkey.

They say it is to preserve the memory of the dead as a guarantee that nothing similar could happen again.

At an open-air ceremony in April at Echmiadzin, the seat of the 17-centuries-old Armenian Church just west of Yerevan, Catholikos Karekin II proclaimed all the dead in what Armenians call the "Medz Yeghern," or "Great Crime," to be saints.

"During the dire years of the genocide of the Armenians, millions of our people were uprooted and massacred in a premeditated way, passed through fire and sword and tasted the bitter fruits of torture and sorrow," the church leader declared.

But since that time Turkey has consistently refused to accept that there was any deliberate attempt to wipe out the Armenians as a people in an act of genocide – a term itself first used in 1943 to refer to Nazi atrocities against Europe's Jews in what became known as the Holocaust.

And as countries around the globe - there are currently 27 of them - have in recent years begun to accept the term to describe the events in Anatolia and beyond from 1915 and up to 1923, successive governments in Ankara have responded fiercely, denouncing such developments as "anti-Turkish."

TURKEY'S VIEWPOINT

Turkey has consistently argued that the Armenians – it puts the total death toll at around only 400,000 – were simply victims of the World War One conflict in in which hundreds of thousands of Muslim Turks also died.

"To ignore this fact and discriminate between pain that was suffered is as questionable historically as it is mistaken morally," Prime Minister Ahmet Davutoglu said in comments on the eve of the Yerevan centenary commemoration this year.

But contemporary photographs, documents and memoirs on display at a museum built in the early 1990s into the hill under the Genocide Memorial – where both Russia's President Putin and France's President Francois Hollande laid wreaths in April – attest to the scale of the "Medz Yeghern."

Scenes of piled corpses, crucifixions, sacked villages with skulls lying in courtyards while Turkish soldiers gaze on are interspersed with portraits of Armenian families in pre-1915 days, smiling into the camera unaware of what was to come – although perhaps with a hint of awareness that Turks had already turned on Armenians in the late 19^th and early 20^th centuries.

The almost normality before the killings began is underlined by a photo of an Armenian football team from Istanbul that played in a Turkish league, of pictures of Armenian recruits and officers of the Turkish army, and of Armenians who held high posts in the Turkish administration.

All the same, some key governments have not yet accepted that the Turkey of those years was guilty of genocide.

U.S. President Barack Obama, who once signalled he might move to recognise that the Armenians had been subject to an attempt to wipe them out, referred only to the "terrible carnage" of the events in a statement on the centenary.

Britain also has steered away from using the term.

Yet Germany, whom many historians say was – under its then rulers – implicated in genocide by aiding the Turks and doing nothing to stop the killings, this year effectively recognized what had happened in a statement from its President Joachim Gauck.

Even in Armenia itself, the events have not always been part of public discussion.

In the Soviet Union, into which the briefly independent country was incorporated from 1921, talking about them was taboo - partly because the Communist Party felt it could encourage breakaway nationalism and partly because the Kremlin sought to keep good relations with Turkey.

It was not until April 1965, on the 50^th anniversary of the arrests in Istanbul, that the first major but unauthorised commemoration, took place when hundreds of thousands of people defied the ban to demonstrate on the streets of Yerevan and other Armenian cities to demand a change in policy.

Taken aback by the strength of feeling, Soviet leaders in Moscow gave way, and authorized the republic's ruling Communist Party and government to create a memorial. Within two years the complex at "Sparrow Castle" was completed.

Today, post-communist Russia supports the Armenian view of the events of 100 years ago.

"There is no, and can be no, justification for the mass murder of people," declared President Vladimir Putin after laying a wreath at the memorial in April. "On this day, we mourn together with the Armenian nation."