Social media pages affiliated with the self-proclaimed Islamic State terrorist organisation claim that the group killed 21 Egyptian workers who had been held captive for weeks in Libya.

The photos showed the workers dressed in orange while being marched down a beach by masked militants with knives being placed on their throats.

The 21 Coptic Christian workers were taken hostage in November and December by the Islamic State’s branch in Libya.

“Soldiers of the Islamic State captured 21 Christian crusaders,” the group said in a statement at the time, accompanied by a set of photos of the hostages.

Photo of what the Islamic State says are the Egyptian workers kidnapped in Libya

Several Coptic Christian Egyptians have been killed in Libya in recent years.

In February 2014, the bodies of seven Egyptian Christians, who had been shot dead, were found near the coastal city of Benghazi.

Another seven Christian men were abducted near the Libyan city of Tripoli in November. One week later, armed men stormed into a house full of Christian workers and kidnapped 13 of them.

In December, physician Magdi Subhi Tawfiq, his wife and his daughter were killed in a terrorist attack at their residence in the Libyan city of Sirte.

Terrorists belonging to Ansar Al-Sharia, Libya’s Al-Qaeda branch, claimed responsibility for their killing.

Two other daughters survived the attack and returned to Egypt.

Egyptians in Libya, especially Coptic Christians, continue to be targeted by local terrorist groups since Egypt declared its support for the Libyan government in its fight against terrorism.

Tens of thousands of Egyptians work in Libya, mainly in the construction industry, as the country is a key destination for Egyptian migrant workers.

An Islamic State affiliated account on Twitter confirms the execution of the workers

Last December, militants loyal to the Islamic State announced they had seized control of the city of Derna, which has a population of 100,000 inhabitants and is 320 kilometres away from the southern shores of Europe.

The city is around 200 kilometres away from the Egyptian border.

Egypt is already battling an insurgency from Ansar Beit Al-Maqdis in Sinai.

Egyptian security officials said the Islamic State has established contact with Ansar Beit Al-Maqdis in Sinai and affiliated terrorist groups in Libya, though the precise nature of these communications is so far unclear.

Libya’s recognised government has been engaged in fierce figting with local terrorist groups since a group known as Fajr Libya (Libyan Dawn) took control of Tripoli in August. Since then, they have setup a rival government and parliament.

Libya’s government has been forced to run a rump state in the east of the country, where the internationally recognised parliament is now based.

The North African country, a major oil producer, has slipped into chaos following a Western backed uprising which toppled long-time dictator Muammar Gaddafi in 2011.

Gadaffi`s regime was deposed in August 2011 after months of NATO air strikes against his strongholds.

He was tortured and murdered alongside 66 of his supporters and government officials in the Libyan city of Sirte in October 2011.