* Turkey denies Armenian killings a century ago was genocide
* Turkey says Senate resolution may harm US-Turkey ties
ANKARA, April 11 (Reuters) - Turkey condemned on Friday a U.S. Senate committee resolution branding the massacre of Armenians by Ottoman forces during World War One as genocide and warned Congress against taking steps that would harm Turkish-American ties.
The nature and scale of the killings remain highly contentious nearly a century after they took place. Turkey accepts that many Armenians died in partisan fighting beginning in 1915, but denies that up to 1.5 million were killed and that this constituted an act of genocide - a term used by many Western historians and foreign parliaments.
The resolution, adopted by the Senate Committee on Foreign Relations on Thursday, called "to remember and observe the anniversary of the Armenian Genocide on April 24, 2014".
"The President should work toward an equitable, constructive, stable, and durable Armenian-Turkish relationship that includes the full acknowledgment by ... Turkey of the facts about the Armenian Genocide," the text of the resolution said.
The Turkish Foreign Ministry said the committee had acted beyond its position, competence and responsibility by adopting a "hastily and ineptly prepared" draft resolution.
"We reject this attempt at political exploitation that distorts history and law and we condemn those who led this prejudiced initiative," the ministry said in a statement.
It said Turks and Armenians could reach a "just memory of the tragic 1915 events" and that an earlier proposal from Ankara to set up a joint historical commission remained on the agenda.
Armenia did not take up the Turkish offer because it regards the genocide as an established historic fact and believes Turkey would use such a commission to press its own version of events.
"It is essential that the U.S. Congress engages in efforts aimed at strengthening our historic alliance ... instead of damaging Turkish-American bilateral ties," it added.
Last December, Foreign Minister Ahmet Davutoglu made Turkey's first high-level visit to Armenia in nearly five years, raising the prospect of a revival in peace efforts between the historical rivals which stalled in 2010.
The legacy of the killings has remained a major obstacle to reviving frozen relations between Turkey and its small former Soviet eastern neighbour.
Armenia accuses the Ottoman authorities at the time of systematically massacring large numbers of Armenians, then deporting many more, including women, children and the elderly and infirm in terrible conditions on so-called death marches.
The issue has long been a source of tension between Turkey and several Western countries, especially the United States and France, both home to large ethnic Armenian diasporas. (Reporting by Tulay Karadeniz; Writing by Daren Butler. Editing by Gareth Jones)