Isis is likely to carry out new terror attacks across Europe in the “near future” as jihadis consider car bombings, chemical weapons and other methods to maximise casualties, security services have warned.

A new report by Europol, the EU-wide law enforcement agency, found that the terrorist group was changing its modus operandi as militants are driven out of key strongholds in Syria and Iraq.

Britain is among the top targets for atrocities, with at least 12 attempted attacks foiled in the past three years, and the threat level could now be increasing with the return of defeated foreign fighters with weapons training and links to Isis commanders.

Gilles de Kerchove, the EU’s counter-terror coordinator, said the danger will last for years as battles against Isis continue in the Middle East and North Africa.

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“These people are trained to use explosives and firearms and they have been indoctrinated by the jihadist ideology,” he added.

“An effective response requires a comprehensive approach and long term commitment.”

Intelligence services estimate that several dozen jihadis under Isis’ direction are already present in Europe with the capability to commit terrorist attacks, but Europol warns of the additional risk of “lone wolf” terrorists who have no direct contact with the group.

While the deadliest attacks so far, in Paris on 13 November 2015, were directed by Isis and carried out by militants deployed from its Syrian territories, the Nice attack and a succession of terrorist murders in France, Belgium and Germany were committed by extremists with no external aid or training.

Europol’s report, by the European Counter Terrorism Centre, said the vast majority of attackers in Europe have been young men with a criminal past, who feel discriminated, humiliated and marginalised in society, and may have mental health issues.

Not all are strict Muslims and may have recently converted to the religion, or solely to Isis ideology, either on their own or through terrorist recruiters.

Terrorism in 2016: Terror attacks in Europe claimed by Isis Show all 9 1 /9 Terrorism in 2016: Terror attacks in Europe claimed by Isis Terrorism in 2016: Terror attacks in Europe claimed by Isis Policemen outside Rouen's cathedral during the funeral of Jacques Hamel, the priest who was killed in a church in Saint-Etienne-du-Rouvray in Normandy on 26 July during a hostage-taking claimed by Islamic State group Joel Saget/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis Two jihadists, both 19, slit Hamel's throat while he was celebrating mass in an attack that shocked France as well as the Catholic Church Joel Saget/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis Muslims place flowers and hold a minute of silence in front of the church if Saint-Etienne-du-Rouvray, western France, where French priest Jacques Hamel was killed on 26 July Charly Triballeau/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis Two people hold each other by the new makeshift memorial in Nice, in tribute to the victims of the deadly Bastille Day attack at the Promenade des Anglais Valery Hache/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis The Islamic State group claimed responsibility for the truck attack that killed 84 people in Nice on France's national holiday. Mohamed Lahouaiej-Bouhlel, 31, smashed a 19-tonne truck into a packed crowd of people in the Riviera city celebrating Bastille Day Valery Hache/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis Police work at a site where a Syrian migrant set off an explosive device in Ansbach, southern Germany, on 25 July, killing himself and wounding a dozen others Daniel Roland/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis A Syrian migrant set off an explosion at a bar in southern Germany that killed himself and wounded a dozen others in the third attack to hit Bavaria in a week. The 27-year-old, who had spent a stint in a psychiatric facility, had intended to target a music festival in the city of Ansbach but was turned away because he did not have a ticket Friebe/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis Police officers walk along train tracks in Wuerzburg southern Germany on 19 July, a day after a man attacked train passengers with an axe. German authorities said they had found a hand-painted IS flag among the belongings of the man, an asylum seeker from Afghanistan, who seriously injured four members of a family of tourists from Hong Kong in his rampage Daniel Roland/AFP/Getty Images Terrorism in 2016: Terror attacks in Europe claimed by Isis German police killed a teenage assailant after he attacked passengers on a train in Wuerzburg, southerg Germany with an axe and a knife on 18 July, seriously wounding three people Karl-Josef Hildenbrand/AFP/Getty Images

“Religion may thus not be the initial or primary driver of the radicalisation process, but merely offering a ‘window of opportunity’ to overcome personal issues,” analysts said.

The report raised concern that Syrian refugees may be targeted by recruiters as Isis seeks to gather support for its cause by “inflaming the migration crisis to polarise the EU population and turn sections of it against those seeking asylum”.

The group uses a network of recruiters as well as a sophisticated propaganda machine churning out videos, magazines, terror manuals and websites aimed at gathering supporters and inciting attacks.

Abu Mohammad al-Adnani, the Isis propaganda chief who was killed in a drone strike in August, released a video in May calling on anyone prevented from travelling to the so-called “caliphate” to wage jihad in their home countries.

“Make examples of the crusaders, day and night, scaring them and terrorising them, until every neighbour fears his neighbour,” he urged ahead of a fresh spate of attacks in Europe.

“Know that your targeting [of] those who are called ‘civilians’ is more beloved to us and more effective, as it is more harmful, painful, and a greater deterrent to them.”

Europol warned that potential targets are difficult to predict as all countries participating in the US-led coalition’s air strikes have been singled out in propaganda videos, with a growing preference for “soft targets” like public transport that have little security and provoke “maximum fear”.

A ‘lone wolf’ attacker used a lorry to kill more than 80 people in Nice on Bastille Day (AP)

“Indiscriminate attacks have a very powerful effect on the public in general, which is one of the main goals of terrorism: to seriously intimidate a population,” the report said, adding that attacking critical infrastructure like power grids and nuclear facilities is “currently not a priority”.

Europol also says the consensus among intelligence agencies in EU member states is that “the cyber capabilities of terrorist groups are still relatively low”, but adds that “the possibility of terrorist-affiliated cyber groups engaging in cyber warfare sponsored by Nation States – those with capacities to engage in this type of attacks – should not be discounted.”

Terrorists are known to have acquired hand grenades, rocket launchers, and high-grade plastic explosives and detonators from organised crime groups in Europe, while Isis magazines contain instructions on making TATP – the homemade explosive used in the Paris and Brussels attacks, as well as the 2005 London bombings.

Europol said suicide bombings, shootings, car rammings and stabbings are likely to remain the main mean of attacks as terrorists turn to the most easily available weapons.

But its report warned that methods used in atrocities in Syria and Iraq may be exported to Europe, including car bombs, kidnappings, extortion and the possible use of chemical or biological weapons.

Moroccan authorities dismantled an Isis cell planning attacks potentially involving chemical weapons in February, discovering biological agents among a cache of weapons from Libya to foil a “catastrophic” attack.

Libyan forces are currently driving Isis out of Sirte but the report warned Libya is still a major base for the group (Getty)

Libya, which remains locked in a continuing civil war following the British-backed ousting of Muammar Gaddafi, threatens to become “a second springboard” for Isis attacks on Europe, Europol’s report warned.

Militants are losing ground in their stronghold of Sirte, but the country is still a major destination for foreign fighters, bolstered by a free flow of weapons and “unlimited places in which jihadists could be trained for future terrorist attacks”.

The report also warned that Isis was not the only group with the intent and capability to carry out atrocities in the West, with al-Qaeda and its former affiliate Jabhat al-Nusra continuing to inspire attacks including the Charlie Hebdo massacre.

Rob Wainwright, the director of Europol, said police and security services were intensifying cooperation to combat the threat, causing an increase in terror arrests and the foiling of several plots.

“This shows that the increased cooperation and exchange of data between all relevant services across Europe is a successful means to mitigate the threat posed by Isis,” he added.

“Nevertheless, this report shows that the threat is still high and includes diverse components which can be only tackled by even better collaboration.”