Turkey's Prime Minister Recep Tayyip Erdogan has offered condolences to the grandchildren of Armenians who were killed by Ottoman soldiers during World War I.
Erdogan made the statement on Wednesday, on the eve of the 99th anniversary of the start of mass deportations of Armenians.
Millions of people of all religions and ethnicities lost their lives in the First World War."
"The incidents of the First World War are our shared pain," Erdogan said.
He acknowledged that the events of 1915 had "inhumane consequences", but also said it was "inadmissible" for the past to be used as an excuse for hostility against Turkey today.
Erdogan's comments were the first overt attempt by a Turkish leader to offer condolences for the killings that some historians consider to be the first genocide of the 20th century.
Armenia has tried to get Turkey to recognise the killings of up to 1.5m people as genocide.
But Turkey says 500,000 people died because of fighting and starvation during World War I and refuses to term the killing of the Armenians a genocide.
"Millions of people of all religions and ethnicities lost their lives in the First World War," Erdogan said.
The arrest and massacre of 2,000 Armenian leaders began in Istanbul on April 24, 1915.
A century later, the killings still fuel bitter controversy, often upsetting relations between Turkey and the West.
But there have been some gradual signs of change.
Ahmet Davutoglu, Turkey's foreign minister, last year called the events of 1915-16 a "mistake" and an "inhuman act" during a trip to the Armenian capital, Yerevan.
Erdogan's statement on Wednesday also called for a dialogue between the two countries and for the setting up of a commission to probe the events surrounding the killings.
"Having experienced events which had inhumane consequences - such as relocation - during the First World War, should not prevent Turks and Armenians from establishing compassion and mutually humane attitudes towards one another," Erdogan said.
It was not immediately clear if the prime minister's words would be enough to thaw relations between the two countries.