ISIS released a video yesterday which called for the slaughter of Egyptian Christians, and showed the last statement from the man allegedly responsible for the Cairo church bombing in December.

The 20 minute video, titled 'Kill all the Kuffar' (Kuffar is Arabic for 'unbeliever') encourages fellow militants to attack and kill Christians across the country, as AMN reports.

The video also features footage a masked man the group named as Abu Abdallah al-Masri and the perpetrator of the Cairo church bombing in December that killed 28 and wounded over 40. Most of the victims were women and children. ISIS previously claimed responsibility for the attack, calling it a 'martyrdom operation' targeted at 'infidels' and 'apostates'.

Egypt's president Abdel Fattah al-Sisi previously identified the bomber as 22-year-old student Mahmoud Shafik, whose assumed name was believed to have been Abu Abdallah al-Masri.

In the video Al-Masri encourages fellow jihadists not to give up, and promises those jailed in Egypt that they will soon be freed.

'Finally, to my brothers in captivity: rejoice, you believers, do not falter or grieve. I swear to God we will very soon liberate Cairo and free you from captivity. We will come bearing explosives, I swear we will, so rejoice you believers,' he said.

Egypt has an estimated population of nine million Christians. Mostly Orthodox Copts, they account for about 10 per cent of Egypt's population, which is overwhelmingly Sunni Muslim.

Last week a Coptic Christian schoolteacher was killed by militants while on the way to work in Sinai, Egypt. The killers are suspected to have been ISIS militants, and the attack was the second killing of a Christian in the area in less than a week. 

In a brutal killing spree in January, five Coptic Christians in Egypt were murdered, all found with their throats slashed.

The full ISIS video can be seen here, though it is expected to be removed by Youtube soon. 

Additional reporting by Reuters