The Islamic State released a five-minute video on Sunday purportedly showing the beheading of 21 Egyptian Christians that they captured in Libya.
The footage released online shows handcuffed hostages wearing orange jumpsuits being beheaded by their black-suited captors on a seashore.
A masked militant, the only one who is not dressed in black, speaks fluent English with a foreign accent is heard saying, "Oh people, recently you've seen us on the hills of Al-Sham (the Levant) and on Dabeq's Plain, chopping off the heads that had been carrying the cross delusion for a long time, filled with spite against Islam and Muslims, and today we are sending another message: oh crusaders, safety for you will be only wishes."
The IS militants in the video are further shown decapitating the hostages with one of them saying towards the end of the clip: "The sea you've hidden Sheikh Osama Bin Laden's body in, we swear to Allah we will mix it with your blood."
Egyptian President Abdel-Fateh el-Sisi has said his country "reserved a right to respond" to the killing of its 21 citizens in the manner and at the time it sets.
"Egypt is able to defeat terrorism; because it does that not only to defend itself, but also to defend the humanity," the president said in his televised speech.
Terming the beheading of the Christians as 'vicious', the Egyptian president said a new series of terrorism is spreading across the world and demanded that all people come together to fight it.
During his speech, el-Sisi offered his condolences to the families of the dead even as he ordered the government to strictly ban Egyptians from travelling to Libya and asked to facilitate the return of others from there.
The president also added that he has ordered the national defence council, country's top security body, to be holding permanently.
He also asked the Foreign Minister to travel to New York and participate in the "fighting terrorism" summit.
Earlier in the day, Egypt announced a seven-day mourning period over the beheading. The Egypt government had previously advised its citizens not to travel to Libya, however, thousands of Egyptians have travelled there in search of jobs.
With inputs from PTI
