Isis fighters routed from their stronghold of Sirte in Libya are likely to try to enter Europe hidden among migrants crossing the Mediterranean in smugglers' boats, Italy has warned.

Hundreds of Isis (Islamic State) fighters are fleeing Sirte after coming under sustained assault from Libyan ground forces and air strikes by US fighter jets and drones.

"The scenario has totally changed and the risk that militants could flee to Europe by sea has substantially increased," said Giacomo Stucchi, president of a parliamentary committee that oversees Italy's intelligence services.

It is feared that if Isis succeeds in reaching Italy, fighters could plan attacks on targets in Europe.


"They are loose cannons, men on the run. We need to understand their intentions - whether they want to disappear without trace or whether they want to continue fighting in the name of their cause," said Stucchi.

The warning was echoed by Pier Ferdinando Casini, the president of Italy's foreign affairs committee.

"There's always a risk of people trying to infiltrate in this way," he said.

"But the priority for us was to liberate Sirte. This is a great victory for the forces of the coalition and the [UN-backed] government of [Fayez] Al-Sarraj."

Libyan forces launched their offensive to reconquer Sirte in June. After weeks of house-to-house fighting, they recently captured several strategic locations formerly occupied by the terrorist group, including the Ouagadougou convention centre, a symbol of the extremists' control of the city.

Libyan officials claim three quarters of the city has now been liberated, a year after it was seized by Isis. There was alarm in Italy in recent days when it was revealed that Isis fighters had left behind graffiti in which they described the city as "the port of the Islamic State - the starting point for Rome".

Isis has often boasted of conquering Rome and the Vatican as key symbols of Christianity, featuring images of St Peter's Basilica in its propaganda videos.

Last week, Italy tightened security controls at commercial ports, creating long delays for passengers and vehicles boarding ferries in cities like Genoa, Palermo and Bari.

There have also been several recent terrorist attacks in Europe carried out by refugees.

Last month, Isis claimed responsibility for two cases in Germany - an axe attack by a 17-year-old Afghan refugee and a suicide bombing by a Syrian refugee which injured about 20 people.

Another Syrian refugee was arrested in July after killing a pregnant woman with a machete in Germany, though police said the murder did not appear linked to terrorism.

Last week, German police arrested another Syrian refugee after receiving a tip-off that he was planning a possible Islamist-motivated attack.

The United Nations has warned against demonising refugees and migrants on the basis of isolated, if devastating, acts of violence.

"We should not forget that the vast majority of refugees are law-abiding and we should not demonise them or see them all as criminals and terrorists because that's not the case," said William Spindler, from the UN refugee agency.