ABU DHABI (AFP) - The United Arab Emirates expressed backing Monday for a strong Egyptian response to video released by the Islamic State group in Libya purporting to show its beheading of 21 Coptic Christians.

Foreign Minister Sheikh Abdullah bin Zayed al-Nahyan said the killings underlined the need for greater support for Libya's beleaguered internationally recognised government, which was ousted from the capital Tripoli last August.

His comments came as Egyptian warplanes carried out at least seven strikes against targets in the extremist stronghold of Derna in eastern Libya.

The UAE "supports, with all its capabilities, Egypt's efforts in eradicating terrorism and violence directed at its nationals and affirms its position in standing alongside and its complete solidarity with it," Sheikh Abdullah told the official WAM news agency.

"The criminals must strongly and decisively receive the punishment they deserve without any hesitancy," he added.

The UAE carried out air strikes from Egyptian bases last year in an abortive attempt to prevent Tripoli's fall to Islamist-backed militia, the US military said.

The Gulf state is part of a US-led coalition carrying out air strikes against the Islamic State in Iraq and Syria (ISIS).

It suspended its participation in sorties after a Jordanian pilot was captured by ISIS in December but resumed it last week after ISIS posted grisly video of the airman's murder.