The European Union denounced Monday the slaughter of at least 28 Ethiopian Christians in an Islamic State (IS) video as a 'criminal' effort to create religious divisions.

"This not a clash of civilisations, this not a fight between Islam and the West," an EU spokesman said in a statement. "This is a criminal misuse of a noble religion to perpetrate terrorist attacks in a struggle for power."

The video released Sunday by the militant group shows militants in Libya shooting and beheading captives, who are described in text captions as "followers of the cross from the enemy Ethiopian Church".

"The EU stands together with the growing number of countries in Africa, which are battling terrorism and radicalisation," the statement said.

"In the Sahel region and in the Horn of Africa, the EU supports regional counter-terrorism efforts and directs its development support to help tackle the root causes of these problems," it added.

Awash with weapons since its 2011 revolt and torn between rival governments and parliaments, Libya is on the edge of all-out civil war as armed groups do battle for its cities and oil wealth.

The Islamic State, which has seized chunks of Syria and Iraq, has won the support of militant groups across Middle East and north Africa. Several Libyan militant groups have pledged allegiance to the militants.

"We will intensify our efforts to work with the African governments and regional organizations," the statement said.

"Only a political agreement can bring sustainable peace in Libya and help the country to effectively fight against Da'esh (IS) and terrorist organisations."