Dabiq ISIS magazine Egyptian Coptic Christians abducted
Islamic State militants claim to have taken 21 Egyptian Coptic Christians hostage in Libya.Dabiq

Egypt is planning to evacuate its nationals from Libya after a jihadi group affiliated to the Islamic State (Isis) claimed the abduction of 21 Egyptian Coptic Christians there, it has been reported.

Pictures showing about a dozen prisoners wearing orange jumpsuits marching on a beach and then forced to kneel at knifepoint in front of by black-clad militants were published by IS mouthpiece magazine Dabiq, earlier this week.

The photos featured in an article titled "revenge for the Muslimat persecuted by the Coptic Crusaders of Egypt".

In it the terror group claimed responsibility for the kidnapping of the 21 Coptic Egyptians who were taken hostage in two separate incidents between the end of December and early January.

The images mirrored those of summary executions carried out and filmed for propaganda purposes by IS in Syria.

The government in Cairo was assessing the authenticity of pictures and laying out an emergency plan to repatriate its nationals stuck in the neighbouring country, Al Arabiya reported, citing local media.

Libya has been is engulfed in fighting since the overthrow of late dictator Muammar Gaddafi in 2011, with Islamist militia groups and pro-government forces currently battling for control of country.

The Egyptian hostages were abducted in Sirte, a coastal city that was Gaddafi's hometown and has fallen in the hands of Ansar al-Sharia, a jihadi movement that pledged its alliance to IS and is designated a terrorist organisation by the UN.

Thirteen were kidnapped from a residential compound that was stormed by masked men who went room to room checking identification papers to separate Christians from Muslims on 3 January.

"They had a list of full names of Christians in the building. While checking IDs, Muslims were left aside while Christians were grabbed," Hanna Aziz, a witness, told AP.

Another seven were abducted a week earlier at a checkpoint while trying to leave the city, according to the BBC.