Egypt has launched air strikes on Islamic State targets in Libya in retaliation to the beheading of 21 hostages by militants linked to the extremist group.
Fighter planes bombed weapons caches and training camps in dawn raids carried out to "avenge the bloodshed", military commanders in Cairo told state broadcasters.
The attacks came after Libyan jihadists loyal to IS - also known as Isis or Isil - posted a video of Coptic Christians from Egypt being massacred.
Dressed in orange overalls, the hostages are seen in the footage being forced to the ground before they are beheaded.
The captives were seized in December and January from the eastern coastal town of Sirte, which is now largely held by Islamist fighters.
Libya's air force was also reported to have carried out strikes in the city of Darna, which was seized by an IS affiliate last year.
The developments have raised fears that IS has established a firm presence in a country less than 500 miles (800km) from the southern tip of Italy.
In the video, a militant suggests that the group now plans to "conquer Rome".
Italy has closed its embassy in Tripoli, the Libyan capital, while reports today suggest that the European country is prepared to seek a United Nations mandate to dispatch troops to Libya.
Foreign Secretary Philip Hammond, meanwhile, denounced the killing of the Egyptian hostages.
"Such barbaric acts strengthen our determination to work with our partners to counter the expanding terrorist threat to Libya and the region," he said.
"Acts of terrorism should not be allowed to undermine Libya's political transition.
"We remain fully supportive of the UN's efforts to build a national unity government for Libya and to bring a political solution to the ongoing security crisis.
"Those who support terrorists can have no part in this process."
The Iraqi Prime Minister, meanwhile, says his country is preparing to retake the city of Mosul from IS.
Haider al-Abadi says the offensive will take place within the next few months.
Sarah Lockett reports.
Article image courtesy of Rob Schleiffert via Wikimedia Commons.