An Iraqi priest forced to flee Mosul has flown to the US to campaign on behalf of persecuted Christians in the Middle East during Pope Francis' landmark visit.

Father Behnam Benoka last year received a phone call from the pontiff after writing to thank Francis for his support of those fleeing Islamic State. The pope reportedly told Benoka, "Know that I am with you in prayer always. I never forget you."

Speaking to the Daily Signal one year on in Washington, Benoka said Christians and other minorities in the Middle East continue to suffer significantly. "We left everything, we lost everything that we had," he said.

"It is very hard so see the suffering. We are losing them. The world is losing Christians from Iraq. That is a big loss for humanitarian heritage. Yes, we would like to live in peace and security. But we would also like to continue our culture. We are going to disappear."

In Mosul, Father Benoka worked as the rector at the seminary. After he fled to a refugee camp near Erbil along with thousands of others from the Ninevah Plains, he established a health clinic, distributing free medicine and heath care to those most vulnerable.

He said on Thursday that he hopes the pope will use his platform to defend persecuted minorities. "I hope... he could [share] our message, to authorities here in Congress, the White House and UN, to speak about our genocide, and to defend us here. That is our hope," Benoka said.

Francis has been vocal in his condemnation of Islamic State, as well as threats to religious freedom all over the world. In July, he compared the suffering of Christians in the Middle East to that of first century Christians, and said that this persecution even today often takes place "under the eyes and in the silence of all".

Before a joint meeting of Congress on Thursday, the pope urged the US to respond compassionately to the thousands who are fleeing war and persecution in Syria, branding the refugee crisis as "of a magnitude not seen since the Second World War".

"We must not be taken aback by their numbers, but rather view them as persons, seeing their faces and listening to their stories, trying to respond as best we can to their situation," he said during his passionate speech.

"To respond in a way which is always humane, just and fraternal. We need to avoid a common temptation nowadays: to discard whatever proves troublesome. Let us remember the Golden Rule: 'Do unto others as you would have them do unto you'...The yardstick we use for others will be the yardstick which time will use for us. The Golden Rule also reminds us of our responsibility to protect and defend human life at every stage of its development."