Dabiq ISIS magazine Egyptian Coptic Christians abducted
Islamic State militants have killed 21 Egyptian Coptic Christians who were held hostage in Libya. Dabiq

Egypt said it has launched air strikes in Libya targeting Islamic State (Isis) positions after the militant group released a video showing the beheading of 21 Coptic Christians.

According to an army announcement on state television, Egyptian forces bombed IS targets in Libya.

"Your armed forces on Monday carried out focused air strikes in Libya against Daesh [IS] camps, places of gathering and training, and weapons depots," the military said in a statement.

Images of warplanes taking off from the bases to conduct airstrikes were also shown.

The reported attack has come shortly after President Abdel Fattah al-Sisi promised strong retaliation against the Islamist militants.

The Libyan military has also invited Egypt to carry out an aerial bombardment in Libya, not just against IS but also against other militias.

"We strongly support Egyptian military intervention to strike Daesh [IS] and other terrorist groups. Libyans are helping the Egyptian army to take revenge on these terrorist forces because Cairo is considered to be a Libyan city," said Libya's top army general Khalifa Haftar.