The Islamic State (Isis) terrorists killed a Christian priest in Syria and cut his body into pieces, before sending it back to his family in a box, according to a Catholic relief agency.

Isis, after kidnapping the priest, had informed his family that they would release him after they pay $120,000 as ransom. After two months, the family of the priest finally managed to raise the money and paid it to Isis.

However, the jihadist group cut the priest's body into pieces and sent it to the family in a box, spokesperson for Aid to the Church in Need John Newton told Christian Post.

Newton said that the priest was just one among hundreds of Arab-Christians who were kidnapped by Isis to raise money to fund its terror activities. And despite taking huge amounts of money from the families of the kidnapped Christians, the victims were tortured and even beheaded, Newton added.

In April 2013, Archbishops of Syriac-Orthodox and Greek-Orthodox Metropolitans of Aleppo Gregorios Yohanna Ibrahim and Boulos Yazigi were kidnapped from the road between Aleppo and the Turkish border.

The two priests were negotiating for the release of two other priests, Michael Kayyal and Maher Mahfouz, who were kidnapped in February 2013.

"No one knows who took the archbishops, nor what their fate was, but the two priests they were trying to free have since been executed," explained Newton.

Last week, Isis kidnapped 250 Christians, including women and children from the Syrian town of Qaryatain. The Syrian Orthodox Archdiocese of Homs was trying to negotiate with the militants to secure the release of the kidnapped Christians.

The Isis fighters in Qaryatain reportedly went around with a list of names. Some of the Christians hiding in the local monastery were also captured and taken away.

In March, Isis militants -- who had kidnapped 217 Assyrian Christians from Al Hasakah province in northern Syria -- had demanded a ransom of $1 million per person.