US President George W. Bush on Wednesday urged Congress to reject legislation that would declare the World War I-era killings of hundreds of thousands of Armenians a genocide.

The resolution would do "great harm" to US relations with Turkey, "a key ally in NATO and in the global war on terror," Bush said outside the White House.

US Secretary of State Condoleezza Rice and Defense Secretary Robert Gates also denounced the measure as the House Foreign Affairs Committee convened for debate later Wednesday.

"The passage of this resolution at this time would be very problematic for everything we are trying to do in the Middle East," Rice said.

Some 70 percent of US air cargo headed for Iraq goes through Turkey, as does about a third of the fuel used by the US military in Iraq, according to Gates.

The bill declares the killings of Armenians between 1915 and 1917 a genocide, though it would have no binding effect on the US foreign policy.

Armenians say more than 1.5 million Armenians were killed in a systematic genocide in the hands of the Ottomans during World War I, before modern Turkey was born in 1923.

Turkey says the Armenians were victims of widespread chaos and governmental breakdown as the 600-year-old empire collapsed in the years before 1923.

Turkey's President Abdullah Gul wrote to Bush on Tuesday, warning that the bill recognizing the World War I mass killings of Armenians as genocide would harm ties between the two allies.

Gul's letter warned of "serious troubles in the two countries' relations" if the bill is passed, Gul's office said in a statement.

(Xinhua News Agency October 11, 2007)