The Islamic State (ISIS) group released a video on Sunday purportedly showing the beheading of Egyptian Coptic Christians the group captured in Libya, reports AFP.

The footage released online shows handcuffed hostages wearing orange jumpsuits being beheaded by their black-suited captors on a seashore in the Libyan capital of Tripoli.

In the latest issue of the ISIS online propaganda magazine Dabiq, the group said 21 Egyptian hostages were being held, and pictures showed a similar background.

The video, titled "A message signed with blood to the nation of the cross", has a scrolling caption in the first few seconds saying it is directed at "People of the cross, followers of the hostile Egyptian Church".

Sunday's video comes just days after ISIS released a video showing the gruesome burning alive of a Jordanian pilot it captured after his F-16 came down in Syria in December.

A spokesman for the Egyptian foreign ministry, Badr Abdelatty, confirmed to AFP in Cairo that 20 Egyptians had been kidnapped in two separate incidents in neighboring Libya.

He did not say when they were seized or specify their religious affiliation, but said seven Egyptians and 13 others abducted separately in Libya "are still being detained" by their captors.

In January, the ISIS affiliate in Libya, known as Ansar al-Sharia, kidnapped 13 Coptic Christians in Sirte. They were reportedly released several days later.

Libya is home to a large community of both Muslim and Coptic Egyptians, with most working in the construction sector.

The country has been plagued by instability and infighting since the toppling of Muammar Qaddafi in 2011, and independent militias still control large part of Libya and regularly fight each other. Terrorist groups have taken advantage of the situation and are training fighters on Libyan soil.

Egypt evacuated its embassy in Tripoli and consulate in Benghazi last year after kidnappers seized Egypt’s cultural attaché and three other embassy diplomats.