Tens of thousands of Armenians gathered in the capital of Yerevan under cloudy skies Saturday to remember mass killings of Armenians by Ottoman Turks.
Rain fell as they placed flowers at a hilltop memorial on the 95th anniversary of the World War I-era deaths.
Armenian President Serzh Sarkisyan thanked countries all over the world, including Turkey, that "understand the importance of preventing crimes against humanity."
Armenia says the killings of an estimated 1.5 million Armenians between 1915 and 1923 constituted genocide, a charge rejected by Turkey. Turkey says the death toll is greatly exaggerated, and that the Armenians died in a civil war that accompanied the collapse of the Ottoman Empire.
U.S. President Barack Obama released a statement Saturday calling the killings "one of the worst atrocities of the 20th century" but avoided using the term, genocide.
Mr. Obama said he is encouraged by dialogue between Turks and Armenians, and within Turkey over what he called "this painful history."
Turkey briefly recalled its ambassador to the United States after a U.S. congressional panel passed a resolution labeling the World War I-era killings a genocide.
Turkish officials have also been pressuring U.S. officials to make sure the measure is not ratified by the full House of Representatives.
The killings, which Armenians call the Meds Yeghern, were also commemorated in several major cities around the world, including Moscow, Beirut and Jerusalem.
The day was also marked by human rights activists in the Turkish city of Istanbul. They gathered outside a railway station holding pictures of Armenians killed during World War One. They later threw flowers into the water a sign or mourning.
This year's anniversary comes as efforts to normalize relations between Armenia and Turkey have broken down.
Despite the renewed tensions, Turkish Prime Minister Recep Tayyip Erdogan has said his government is committed to normalizing ties with Armenia.
Some information for this report was provided by AFP, AP and Reuters.