The head of Parliament has warned the United States Congress not to pass an Armenian genocide bill, saying in a letter to the House speaker that the move would harm bilateral ties, his office said Sunday.

The speaker of Parliament, Koksal Toptan, said in his letter to the speaker, Nancy Pelosi, that "it might take decades to heal negative effects" of the bill if it passed, Toptan's office said in a statement.

The bill would declare the killings of Armenians from 1915 to 1917 a genocide, although it would have no binding effect on U.S. foreign policy. The House Foreign Affairs Committee is expected to consider the legislation this week.