Egypt has offered to evacuate thousands of its citizens from Libya after Islamic State (Isis) released pictures showing 21 kidnapped Egyptian Christians paraded in orange jumpsuits. Egypt said it had no choice but take urgent measures on Friday with Isis expanding fast across Libya, its war-stricken neighbour. "We are helping them," Cairo's foreign ministry spokesman, Badr Abdelatty, said. "If they would like to come back from Libya, we are facilitating their return to their home country." The Coptic Christian guest workers were kidnapped in Sirte, on Libya's coast, by Isis units based there in two operations in December and January. There have been demonstrations in Cairo by families calling for their release, but the government says it has had problems making contact with the abductors. "There should have been more attempts by the government to intervene," Hanna Aziz, a fellow worker who escaped the Sirte kidnappings, said. "We are all Egyptians, regardless of our religion." Photographs showing the men paraded by black-clad gunmen were published this week in Dabiq, an Isis online magazine, with several recognised by relatives. The militant group has expanded rapidly across Libya, its ranks bolstered by the arrival of foreign fighters from across the Middle East, triggering fears Libya's war will spill over its borders. The magazine depicts the handcuffed men walking and kneeling in a style reminiscent of photographs showing western hostages in orange jumpsuits in Iraq and Syria. Isis says the kidnappings are in response to the alleged killing of two women in Egypt.