The extremist group posted a video online in February 2015 of the beheadings, sparking international condemnation and Egyptian air strikes against jihadist targets in Libya
Libya says remains found of Copts beheaded by ISIL on beach
The remains have been unearthed of 21 Coptic Christians beheaded by jihadists on a Libyan beach two years ago, the interior ministry said on Saturday.
"The heads are separated from the bodies clad in orange jumpsuits, hands bound behind the back with plastic wire," said the ministry's unit for fighting organised crime in the city of Misurata.
It said the bodies of 20 Egyptians and a man of unknown African nationality were unearthed from a mass grave south of the one-time jihadist bastion of Sirte, 450 kilometres east of Tripoli.
Friday's find came after confessions by ISIL prisoners, the unit said, adding that the remains had been transferred to Misurata for forensic examination.
The unit, which answers to the interior ministry of Libya's UN-backed Government of National Accord in Tripoli, did not give a date for the possible repatriation of the remains for burial.
Egypt's foreign ministry said on Saturday it had been informed about the discovery of the mass grave.
"The Egyptian embassy has been communicating since Friday with the Libyans with co-ordination with the Egyptian ministry of defence to secure their return to Egypt," a spokesman said.