A Christian persecution watchdog group has appealed to the international community to quickly intervene in the case of 180 Assyrian Christians whose fate has been sealed for execution by the Islamic State jihadist group after a failed negotiation for their ransom.

Demand for Action spokesperson Diana Yaqco said the international community needs to act immediately to help rescue the Assyrian Christians as ransom demands set by the ISIS seems "unbearable'' for the community to produce.

"We plead and beg the international community to intervene immediately," Yaqco said, according to the Christian Post.

"We have been driven out of our ancestral lands. We have been killed and crucified. The international community must act now to save lives of others kidnapped,'' she added.

The appeal was made following the release of an ISIS video showing the executions of three of the Assyrian Christian hostages.

"We condemn this latest act of barbarism in the strongest possible terms. The systematic ethno-religious cleansing of Assyrians/Syriacs/Chaldeans continues. They are helpless. They are children. They are women. They are somebody's father and brother," Yaqco pointed out.

The Islamic State terror group earlier said it will be executing 180 Assyrian Christians who were kidnapped in mass raids in February after negotiators reportedly failed to meet ISIS high asking price to free the hostages.

The hostages are reportedly part of the 230 people kidnapped by the ISIS in February from villages in the Khabur river valley in Syria, the Christian Post said.

Last week, ARA News reported that the terror group had asked for $12 million for the release of the Assyrians, a sum deemed "unbearable" by the community.

"The negotiations, led by Bishop Ephrem Otnaial, head of the Church of the East in Syria, have been suspended due to unbearable demands of the terror group," said Yaqco.

A member of the Civil Peace Committee in Tel Temir, who chose to remain anonymous, said "internal rifts" have emerged among Assyrian officials on how to gather the money.

Syrian Catholic Archbishop Jacques Behnan Hindo disclosed that negotiators had managed to convince the ISIS to lower the asking price of initially $23 million to free 230 people to a "much, much less'' amount without mentioning the figure.

"Therefore, now, the biggest obstacle regarding the release of our Assyrian brothers is no longer money, but the difficulty of how to organise the phase of liberation," Hindo said.

The ISIS has since released only small groups of hostages it kidnapped from Khabur, said the Christian Post.