The Islamic State (Isis) has executed three Assyrian Christian hostages who were among 200 Christians abducted in February 2015, according to human rights organisations. The Assyrian Human Rights Network said the three men were killed two weeks ago during the Muslim holiday of Eid al-Adha, but a video of the execution surfaced only in October.

The footage shows IS militants wearing camouflage gear and black balaclavas shooting the captives in the back of the head after they introduce themselves to the camera. The hostages – Ashur Abraham, Bassam Isa Mishael and Abd al-Masih Izarya Nwiya – are seen dressed in the orange jumpsuits that the jihadist group has used for other killings.

After the execution, three more captives are seen appealing for the payment of their ransoms, which amount to $50,000 ($33,000) per person. The Assyrian network said there are 187 other Assyrian captives, including women, teenagers and children, currently being held by IS. "The total ransom amounts to $9.5m, which must be paid to secure their release," Dr Nicholas al-Jeloo, an expert on Assyrian monasteries in Iraq from the University of Melbourne, wrote on Facebook.

The hostages were kidnapped by IS in February this year after a three-day assault on a chain of 10 Syrian villages. In August, the jihadist group captured 250 Syriac Orthodox and Syriac Catholic families after seizing the key town of Qaryatain, in the central Homs province, from forces loyal to president Bashar al-Assad. Sources from A Demand for Action (ADFA), an organisation campaigning for Christian minorities in the country, said that 300 families managed to flee from the area.