The UN mission in Libya condemned on Monday the killing of 21 Egyptian Copts by Daesh militant group.
The group's actions should be "rejected and denounced by all Libyans", describing the apparent beheadings as a "terrorist crime against these guest workers from neighboring Egypt", said the mission in a statement.
The mission offered its condolences to the families of the victims.
It urged all sides concerned in Libya to work for peace in their country to abort terrorists' plots to exploit political chaos and seize control.
Daesh released a video on Sunday showing the beheading of 21 Egyptian Coptic Christians.
President Abdel Fattah El Sisi said his country reserved the right to punish these murderers as he called a meeting of security chiefs and declared seven days of mourning after the video was released.
The footage released by IS online shows 21 handcuffed hostages wearing orange jumpsuits being beheaded by their black-suited captors in a coastal area the group said was in the Libyan province of Tripoli.