US President Barack Obama on Thursday described the World War I massacre of Armenians as "terrible carnage", but avoided the term genocide, as tempers flared ahead of the 100th anniversary of the bloodshed.

US President Barack Obama on Thursday described the World War I massacre of Armenians as "terrible carnage", but avoided the term genocide, as tempers flared ahead of the 100th anniversary of the bloodshed.

Friday marks a century since the start of the massacres waged by Ottoman forces, which Armenia says killed 1.5 million people between 1915 and 1917.

Modern Turkey, the successor state to the Ottomans, rejects the term "genocide," arguing that 300,000 to 500,000 Armenians and as many Turks died.

The deaths remain a bone of contention today between the two countries and a sensitive topic for Armenians around the world -- including in the US, where local groups were outraged at Obama's choice of words.

"The Armenian people of the Ottoman Empire were deported, massacred, and marched to their deaths. Their culture and heritage in their ancient homeland were erased," Obama said in a carefully worded statement.

"Amid horrific violence that saw suffering on all sides, one and a half million Armenians perished."

He said Armenians had made valuable contributions in the countries where they settled, including the United States.

"Against this backdrop of terrible carnage, the American and Armenian peoples came together in a bond of common humanity," he said.

The White House has avoided calling the incident a genocide, though last month US lawmakers introduced a resolution urging Obama to recognize the killings as such.

During his 2008 campaign for the White House, then senator Obama had pledged to "recognize the Armenian genocide".