Prince Charles joined the Archbishop of Canterbury and Pope Francis in offering "specia prayers" and sympathy to the Coptic Pope Tawadros II after 24 people were killed in a suicide attack in Egypt.

The Prince of Wales released a statement on Monday afternoon expressing sympathy over the "unbearably inhuman attack" in Cairo on Sunday.

"I can only begin to imagine the dreadful shock and grief that Copts, and indeed all Egyptians, must be feeling and my heart goes out to the families and loved ones of those who have been killed and wounded," he wrote.

He told the head of the Coptic Church: "I wanted to assure Your Holiness that Copts everywhere, and especially in Egpyt, are in my thoughts and special prayers as they try to cope with the loss, pain and fear that the attack has inflicted upon them."

Charles joined Justin Welby who described the dead as "martyrs for Christ" and called on followers to "pray in lament, protest and in hope".

Pope Francis also called Pope Tawadros II to express his condolences and closeness to the victims.

The calls come after a suicide bombing near St Mark's cathedral in Cairo, the home of the ancient Christian group, killed 24 and wounded dozens more.

Three days of national mourning has been declared in Egpyt and President el-Sisi attended a state funeral for the victims on Monday.

Bishop Angaelos, general bishop for the Coptic Church in the UK said the attack was "difficult to comprehend".

He wrote in a statement on Monday: "We have seen recurring acts of violence against Christians and Christian communities in Egypt. Time and time again, very few, if any, perpetrators have been brought to justice, and we subsequently continue to witness an escalation of these attacks.

"This is not a matter of blame, but accountability, with an expectation that barbaric acts such as these should never occur, but if they do, that their perpetrators are rightly and fairly held to account. This is not a call for vengeance, but a deterrent against similar future plans and aspirations."