Cairo, Feb 16 (IANS): Egyptian President Abdel Fattah al-Sisi said Monday that his country reserves the right to respond at the proper time to the killing of 21 Coptic Egyptians in Libya by Islamic State (IS) militants, according to a Xinhua report.

The president said that Egypt would be able to defeat terrorism because "Egypt is defending humanity".

On Sunday, the IS militant group published a video purportedly showing the beheading of 21 Egyptian Coptic Christians abducted in Libya. Later, the Egyptian Orthodox Church confirmed the killings.

The Egyptians were abducted in the Libyan city of Sirte in two separate incidents in December and January, only a week apart from each other.

Sisi held an urgent meeting of the National Defence Council Sunday to discuss the killing of the Egyptian Christians.

He urged the government to move swiftly to assist the families of the victims.

"We all need to be united to fight terrorism," Sisi said.

The Egyptian president declared a seven-day mourning and also ordered the government to enforce a travel ban on Libya.

Libya has been mired in chaos and civil war since October 2011, when the North Atlantic Treaty Organisation (NATO) began supporting anti-Gaddafi rebels, ultimately resulting in the toppling of the Gaddafi regime.