A Syrian priest who escaped after being held captive by Islamic State has spoken of his great relief that relics from his monastery survived the militants' insurgency.

Father Jacques Mourad told Catholic News Agency (CNA) that although his Mar Elian monastery was desecrated by ISIS, the relics of its fourth-century namesake remain intact.

"Mar Elian was a hermit who lived in the fourth century, and his relics were kept in the monastery dedicated to him," he said.

"After the destruction of the monastery, we thought his relics were lost, but instead we were able to find them. This gave us great consolation."

ISIS attacked the tomb of Mar Elian because "they cannot accept that the cities they seize have places where tombs or relics of saints are kept. They believe that there is no need for a tomb, as once a person passes away, his existence is over on earth," the priest added.

Fr Mourad was abducted last year and held captive for almost three months in Raqqa, ISIS' capital in Syria.

After his release, he told members of Rome's Foreign Press Association: "During these 84 days that I was a prisoner in this bathroom in Raqqa, it could be said that it was one of the most difficult experiences that a person can go through; that of losing one's liberty. For me it was also a very intense experience, from the spiritual point of view."

He said that there were very dark moments when he was threatened with execution. "It was very difficult above all when they said, 'Become Muslim or we'll cut your head off,'" he said.

"This is the miracle the Good Lord gave me – while I was a prisoner I was waiting for the day I would die, but with a great inner peace," the priest told Italian TV 2000 in a separate interview.

"I had no problem dying for the name of Our Lord; I wouldn't be the first or the last, just one of the thousands of the martyrs for Christ," he added.

Fr Mourad said he was repeatedly asked to declare his faith and was threatened with death if he did not convert.

"Almost every day there was someone who came to my prison and asked me 'what are you?' I would answer: 'I'm a Nazarene, in other words, a Christian.' 'So you're an infidel,' they shouted. 'Since you're a Christian, if you don't convert we'll slit your throat with a knife.'"

Despite the threats, the priest said he refused to renounce Christ. He credits a Muslim friend and the Virgin Mary for his escape.

"I want to thank all those who prayed for my liberation," he said.

"It's truly a miracle that a priest has been freed from the hands of the Islamic State. A miracle that the Virgin Mary worked for me."

Looking to the future, Fr Mourad told CNA that at his monastery, "we have always hoped to welcome everyone. Mar Elian was really a sign of hope for the Syrian people."

"Everything changed when I was taken hostage. But we can still build something," he said. "We must, however, await the end of this war."