The Prince of Wales has sent a letter professing his "profound sympathy" and heartbreak over the persecution of Christians and other religious people in Iraq.

Charles described his sadness at what he called the "unbearable and barbaric persecution" of certain religions in the war-torn country, in a letter published on the website of the Chaldean church.

The signed letter, accompanied by a donation to the charity Aid to the Church in Need, was sent last month and addressed to Baghdad-based Archbishop Louis Sako, head of the Chaldean Catholic Church.

The Prince said those involved were in his prayers, and spoke of a "fervent hope" that the "diabolical evil" behind the persecution can be overcome.

In a letter responding to the donation and Charles' words, Archbishop Sako said he was moved by the gesture, and urged the international community to continue to help.

He wrote: "Our Christian community in Iraq has endured massacres, atrocities and other human rights abuses by the terrorist armed group calling itself the "Islamic State" (IS), for the reason of their Faith ... we ask yo ur Highness to encourage the international community to preserve the lives and dignity of the huge number of people affected by this disaster."

Clarence House said they would not comment on private correspondence.