Ansar Beit al-Maqdis announced in an audio recording posted via its Twitter account late on Sunday that it had pledged allegiance to Abu Bakr al-Baghdadi, the leader of "Islamic State" (IS). An unidentified speaker on the recording said that al-Baghdadi had been "chosen by God" to establish a new Islamic caliphate.

"Therefore, we have no alternative but to declare our pledge of allegiance to the caliph... to listen and obey him... and we call on all Muslims to pledge allegiance to him," the speaker said.

The group also called on Egyptians to rise up against "the tyrant," apparently referring to President Abdel-Fattah el-Sissi, who was elected earlier this year, and as army chief had toppled democratically elected Islamist President Mohammed Morsi last year.

"What are you waiting for after your honor has been violated and your blood spilled... by this stupid tyrant and his soldiers," the recording said.

The statement also criticized Morsi and his supporters, who have been subjected to a government crackdown since el-Sissi took office.

"Humiliating non-violence will not be of use to you, nor heretical democracy, and you have seen what happened to its adherents," it said.

The Sinai Peninsula-based group, which formed following the overthrow of long-time President Hosni Mubarak in 2011, has claimed responsibility for a number of deadly attacks on members of Egypt's security forces. It has also conducted cross-border raids in Israel.

Some have described the group's pledge of allegiance to IS as the most significant pledge of support for the Islamist fighters outside of Syria and Iraq.

Fate of al Baghdadi unclear

Meanwhile, the condition of al-Baghdadi remained unclear on Monday, 24 hours after Iraqi officials had said that the IS leader had been wounded in an airstrike in Anbar province as he was meeting with fellow militants.

Officials at the Pentagon said they had no information about such a strike or the fate of al-Baghdadi.

pfd/nm (AFP, AP)