A Syrian archbishop visiting Philadelphia has called the United States' reluctance to offer asylum to persecuted Christians "unjust."

Aleppo Archbishop Jean-Clement Jeanbart made the remark Tuesday as he and an Iraqi counterpart appealed to the American people for help withstanding Islamic State oppression.

The rise of the Islamic State group has forced hundreds of thousands of Syrian and Iraqi Christians from their homes, threatening a religion that has survived in the region for 2,000 years. Refugees have flooded unoccupied cities including Erbil in the Kurdistan region of Iraq and neighboring countries including Jordan and Turkey.

The Knights of Columbus has contributed more than $3 million for homes, schools, food and health care. It says it's launching a fundraising and advertising campaign to help refugees.

The U.S. Department of State hasn't returned a message seeking comment on what the Syrian archbishop said.