Wearing black hijabs, Greta Ramelli, 20, and Vanessa Marzullo, 21, speaking to the camera, said: "We are in big danger and we could be killed." The video message, posted on YouTube and thought to be genuine, marks a grim start to 2015 for their families in Italy but does prove that they are still alive.

The two women, who were working as aid volunteers on health and water-related projects, were kidnapped near Aleppo last July by armed men only days after arriving in Syria. Before the release of the video message, they had last been seen on August 1.

It is thought they are being held by Jabhat al-Nusra, the Syrian branch of al-Qaeda, and not by the Islamic State of Iraq and the Levant, which has become notorious for beheading its captives, including five British and American journalists and aid workers and numerous captured Syrian soldiers and Kurdish fighters.

"We supplicate [sic] our government and its mediators to bring us back home before Christmas," the young women say in the video, which was shot earlier in December. "The government and its mediators are responsible for our lives." Their families were criticised in Italy for allowing their daughters to travel to such a dangerous place, but their parents said they were determined and there was little they could do to stop them.

Ms Ramelli's mother, Antonella, said that from a young age her daughter had wanted to help others and had started helping in a retirement home when she was 12.