African Church leaders have responded to the reported Dec. 26 execution of 11 Nigerian Christians by a terrorist group affiliated with the Islamic State.

“We woke up a day after Christmas to the horrible news of the gruesome decapitation of Christian hostages by the Islamic State terrorists,” Fr. Benjamin Achi told ACI Africa Dec. 28.

Achi is director of communications in Nigeria’s Diocese of Enugu, where abductions targeting priests have been on the rise in recent months.

The priest’s comments referred to a Dec. 26 video depicting militants beheading 10 blindfolded captives, and shooting an eleventh.

The West African province of Islamic State, which broke off from Boko Haram in 2016, said the killings were revenge for the deaths of Islamic State’s caliph, Abu Bakr al-Baghdadi and other IS leaders, who were killed by a U.S. raid in October.

The captives were taken in recent weeks from the Maiduguri area in Borno state, the IS claimed.

Achi said the December killings might portend even more Islamist violence in Nigeria.

“This latest development gives serious cause for worry, especially in the wake of the latest move by the federal government of Nigeria to throw wide the borders of the country for anyone who wishes from any part of the continent to come in without visas and proper documentation,” the priest told ACI Africa.

The priest was referring to new visa regulations in Nigeria, which make it easier for Africans to enter the country. The regulations have been widely criticized within Nigeria.

“We are indeed concerned that this decision would facilitate the influx of more of these terrorists from other parts of Africa into Nigeria,” Achi said.

“Christians in all parts of Nigeria have been apprehensive overtime and have seen themselves as clear targets of the endless acts of terrorism being witnessed in the country,” Achi told ACI Africa

On Dec. 28, Cardinal Robert Sarah, prefect of the Vatican’s Congregation for Divine Worship and Sacraments, tweeted about the Dec. 26 killings.

“In Nigeria, the murder of eleven Christians by mad Islamists is a reminder of how many of my African brothers in Christ live faith at the risk of their own lives,” Sarah wrote.

“These baptized are martyrs. They have not betrayed the Gospel,” they have not betrayed the Gospel," the cardinal added.

Archbishop Ignatius Kaigama of Nigeria’s Abuja Archdiocese sees the Christmas Day action by the IS as part of a continued effort to promote antagonism between Christians and Muslims in the country and region.

“They are trying to create a situation of war,” Kaigama told Vatican Radio.

“They want to see Muslims and Christians fighting.”

According to the archbishop, IS members hope that in the midst of the confusion, they might “have the upper hand and be able to destroy Christians, take over the country and even the neighboring countries.”

A version of this story was previously reported by ACI Africa, CNA's African news partner. It has been translated and adapted by CNA.