By Adrian Croft and Ayla Jean Yackley

BRUSSELS/ISTANBUL (Reuters) - The European Parliament backed a motion on Wednesday that calls the massacre a century ago of up to 1.5 million Armenians by Ottoman Turkish forces a "genocide", days after Pope Francis triggered fury in Turkey by using the same term.

Although the resolution repeated language previously adopted by the parliament in 1987, it could stoke tensions with EU candidate nation Turkey. Turkish President Tayyip Erdogan said even before the vote took place that he would ignore the result.

After the vote, the Turkish foreign ministry accused the European Parliament of attempting to rewrite history.

Muslim Turkey agrees that Christian Armenians were killed in clashes with Ottoman forces that began on April 15, 1915, when large numbers of Armenians lived in the empire ruled by Istanbul, but denies that this amounted to genocide.

Armenia, some Western historians and foreign parliaments refer to the mass killings as genocide.

Voting by show of hands, European lawmakers overwhelmingly backed the motion stating that the "tragic events that took place in 1915-1917 against the Armenians in the territory of the Ottoman Empire represent a genocide".

Armenia's Foreign Minister Edward Nalbandian hailed the resolution as a move aimed at defending human rights.

"The Resolution contains an important message to Turkey to use the commemoration of the centenary of the Armenian Genocide to come to terms with its past, to recognize the Armenian Genocide and thus pave the way for a genuine reconciliation between Turkish and Armenian peoples," he said in a statement.

Pope Francis sparked a diplomatic row last Sunday by calling the killings "the first genocide of the 20th century". His remarks prompted Turkey to summon the Vatican's ambassador to the Holy See and to recall its own.

The European Parliament sprang to the pope's defense, commending the message the pontiff delivered at the weekend.

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"IN ONE EAR, OUT THE OTHER"

Turkey is a candidate country to join the 28-nation EU but accession talks have dragged on for years with little progress.

Earlier, Erdogan told a news conference that "whatever decision the European Parliament took on Armenian genocide claims would "go in one ear and out the other".

"It is out of the question for there to be a stain, a shadow called 'genocide', on Turkey," he said at Ankara airport before departing on a visit to Kazakhstan.

Last year, when he was Turkey's prime minister, Erdogan offered what his government said were unprecedented condolences to the grandchildren of Armenians killed during World War One.

Wednesday's resolution said such statements were a step in the right direction, but legislators urged Turkey to go further.

In a statement after the vote, Turkey's foreign ministry said lawmakers who backed the resolution were in partnership with "those who have nothing to do with European values and are feeding on hatred, revenge and the culture of conflict".

(Additional reporting by Humeyra Pamuk and Ece Toksabay in Ankara, Francesco Guarascio in Brussels, Hasmik Mkrtchyan in Yerevan; Editing by Gareth Jones)