Washington Sponsors of a long-debated congressional resolution to officially recognise the Armenian genocide cleared a key hurdle by a one-vote margin on Thursday, but face a tough battle ahead to bring the measure before the House.

The resolution passed the House Foreign Affairs Committee 23 to 22 over opposition from members of both parties who warned it could damage US relations with Turkey, an important ally.

Panel Chairman Howard L. Berman (D-Valley Village) pressed for the vote, even after receiving a call from Secretary of State Hillary Rodham Clinton expressing concern it could "impede progress on normalisation of relations" between Turkey and Armenia, according to an administration spokesman.

But Berman said that the US, as a leader in promoting human rights, had a "moral responsibility" to pass the resolution.

"Perhaps there will be consequences... But I believe that Turkey values its relations with the United States as much as we value our relations with Turkey."

The vote came in a packed meeting attended by three elderly genocide survivors, who support the measure. Pointing to the survivors — ages 97, 98 and 105, Rep Gary L. Ackerman (D-NY) said:

"They're here for justice. How long can they wait?"

The Turkish government has disputed the First World War era killings of Armenians by the Ottoman Turks were genocide, contending both Turks and Armenians were casualties of the war, famine and disease.

But historical evidence and authoritative research support the term.

The resolution has been closely followed by California's large Armenian American population, and is backed by much of the state's congressional delegation.

The tight vote underscored the challenge facing the resolution's sponsors in winning House approval.

"We have our work cut out for us," said Kenneth V. Hachikian, chairman of the Armenian National Committee of America, adding he was "extremely disappointed" in the Obama administration's position.

In Southern California, the vote drew passionate and mixed reactions.