ISIS have released another video showing the apparent beheading of a Christian man who identified as being a citizen of South Sudan.

The video, which was released by ISIS' faction in Libya, purportedly shows the captive wearing an orange jumpsuit making a short statement in which he gave his name and nationality.

The man was then shown being forced to his knees and beheaded.

His executor justified the murder on the grounds of revenge for persecution of Muslims in South Sudan.

"This is a message to our Muslim brothers in South Sudan who are suffering injustice, uprooting and slaughter at the hands of the Christian aggressors," said the masked ISIS fighter, who was dress in black.

"We are conveying good news to you that Allah has deployed the soldiers of the caliphate to avenge for you and defend you.

"We will cut every hand that hurt you. O' Christians in South Sudan know that as you kill you will be killed and as you displace our brothers we will do the same... No safety or shelter for you except that of the Islamic State.. We will fight all of you as you fight us".

The video, which is yet to be verified, was released from ISIS in Cyrenaica, in Libya. The film also showed a Libyan soldier named as Faraj Al-Saiti, being shot, the Libya Herald reported. It is thought the video was filmed near Derna, northeast Libya.

South Sudan is the world's newest country and gained independence from Sudan to the north which is 97 per cent Islamic.

The International Religious Freedom Report in 2014 did not document any systematic discrimination against the 20 per cent Muslim population in South Sudan, which is a secular state according to the constitution.