Several world leaders including the presidents of France and Russia attended the memorial for the victims in Armenian capital, Yerevan.
Armenia is hosting a series of ceremonies in commemoration of the 100th year anniversary of the mass killings of Armenians by Ottoman Turks.
Several world leaders including the presidents of France and Russia attended the memorial for the victims on the outskirts of the capital, Yerevan with French President Francois Hollande saying:
"We will never forget the tragedies that your people have endured."
Also Russian President Vladimir Putin said:
"There cannot be any justification for mass murder of people. Today we mourn together with the Armenian people."
About 1.5 million people were reportedly killed in the 1915 genocide, however Turkey insists that the figure is much smaller.
Turkey also strongly opposes the use of the word 'genocide' to describe the killings and this has soured relations between Turkey and Armenia.
While Turkey accepts that atrocities were committed, they argue that there was no systematic attempt to destroy the Christian Armenian people, asserting that many innocent Muslim Turks also died in the turmoil of war.
Meanwhile Turkey has also said a memorial service will be held in the country today, Friday to mark the 100th anniversary of the start of the Battle of Gallipoli and "share the pain" of Armenians, this is according to the country's prime minister, Ahmet Davutoglu.
But the Armenian President Serzh Sargsyan has accused Turkey of "trying to divert world attention" from the Yerevan commemorations.
Earlier on Thursday, the Armenian Church canonised the 1.5 million people it says were killed in the massacres and deportations, saying it wanted to proclaim the martyrdom of those who died for their faith and homeland.