A series of attempts to carry out lethal attacks on Christmas markets and shopping centres across Europe, including Britain, were foiled before the Berlin murders. The security operations, according to senior sources, were carried out in direct response to information about terrorist threats linked to Isis.

In Britain, counter-terrorism officers stated that a “significant plot” inspired by Isis had been halted. The alleged targets, say security sources, were one or more shopping centres crowded in the run-up to Christmas. Four men in Derby, another one at Burton-on-Trent in Staffordshire and a woman in London, aged between 22 and 36, were arrested ten days ago in connection with the alleged plot, with the recovery of material which could be used for making bombs. On Thursday, two of the men, aged 22 and 27 and from the Derby area were released without charge. The other four people remain in custody.

The strong possibility of terrorist acts during the Christmas period has been mentioned publicly by government bodies and repeatedly in exchange of intelligence between allied security agencies. Isis has also been publicly exhorting its followers to carry out attacks.

The failure of the German authorities to prevent the murders of 12 people, despite these repeated warnings, will raise further questions about their conduct, already being severely criticised, over what has unfolded.

Five men, aged 26 to 37, were arrested last month in Marseilles and Strasbourg five days before the opening of a Christmas market, annually attracting two million visitors, in Strasbourg.

French authorities said the suspects, of North African background, were planning an “imminent” attack under the direction of an Isis commander based in Syria who sent his orders via encrypted mobile apps. Police found pistols and a sub-machine gun in their raids. French Interior Minister Bernard Cazeneuve disclosed that an investigation had been launched following a tip-off by a “partner country”, refusing to specify which one it was.

Who is the prime suspect in the Berlin Christmas market attack?

Ten young men, most of them in their teens, were arrested in Belgium last week allegedly for plotting to attack a Christmas carnival. Eric Van Der Sjipt, a spokesman at the office of prosecution, claimed the suspects had received instructions online on making an explosive device as well as various methods which can be used to kill.

Germany had already experienced a recent attack, albeit a failed one, before Berlin. A 12 year old boy, of Iraqi origin, was arrested earlier this month in Ludwigshafen after attempting to detonate a nail bomb in the town’s Christmas market.

Berlin Christmas market lorry attack Show all 18 1 /18 Berlin Christmas market lorry attack Berlin Christmas market lorry attack Several people have been killed after a lorry drove into crowds at a Christmas market in Berlin REUTERS/Fabrizio Bensch Berlin Christmas market lorry attack 'At least nine' people have been killed and more than 50 injured. AP Berlin Christmas market lorry attack Emergency Services rush a Berlin market victim to an ambulance Associated Press Berlin Christmas market lorry attack Police cordoned off the square at Kaiser Wilhelm Memorial Church following the incident REUTERS Berlin Christmas market lorry attack Rescue workers inspect the lorry that crashed into a Christmas market close to the Kaiser Wilhelm memorial church in Berlin EPA Berlin Christmas market lorry attack Emergency crews inspect the lorry that ploughed into a Berlin Christmas market, killing at least nine people AFP Berlin Christmas market lorry attack Fire crews attend the scene of the attack AFP/Getty Berlin Christmas market lorry attack Armed police secure the site of a lorry attack at a Christmas market in Berlin REUTERS Berlin Christmas market lorry attack Crushed debris is visible beneath the wheels of the vehicle REUTERS Berlin Christmas market lorry attack An injured man is pushed to an ambulance REUTERS Berlin Christmas market lorry attack Medics attend an injured person after the lorry attack which killed at least nine and injured more than 50 people AFP/Getty Berlin Christmas market lorry attack Firefighters examine the lorry which was rammed into a Berlin Christmas market REUTERS Berlin Christmas market lorry attack A person is carried into an ambulance REUTERS Berlin Christmas market lorry attack View of the lorry that crashed into a Christmas market in Berlin, killing at least nine and injuring at least 50 people AFP/Getty Berlin Christmas market lorry attack Rescue workers push a person on a stretcher to an ambulance Getty Berlin Christmas market lorry attack Firefighters assess the damage after the lorry rammed the Christmas market, killing 'at least nine', and injuring more than 50 people AP Berlin Christmas market lorry attack Firefighters stand beside a toppled Christmas tree at the site of the suspected terrorist attack in a Berlin Christmas market AP Berlin Christmas market lorry attack Damaged stalls at the scene of the incident at a Berlin Christmas market where at least nine people have been killed EPA

Last month the US State Department warned American citizens travelling to Europe of possible terror attacks. It said “credible information indicates that the Islamic State (Isis) al-Qaeda and their affiliates continue to plan terror attacks in Europe with a focus on upcoming holiday season and associated events”.

Isis leaders have called for attacks to be carried out at crowded places such as markets and shopping centre. Last month the group’s magazine, Rumiyah, even suggested the use of a vehicle to carry out atrocities, specifying the Bastille Day massacre in Nice, in the summer, in which a truck was used to take 86 lives, as an ideal template to cause maximum damage “behind enemy lines”.