Police have arrested the wrong man in the hunt for a lorry driver who killed at least 12 people in a suspected terror attack on a Christmas market, according to German media reports.

Sources told Die Welt a Pakistani man detained near the scene of the massacre in Berlin is not believed to be linked to the atrocity, meaning the attacker is still on the run.

"We have the wrong man," the newspaper quoted a Berlin police official saying. "And therefore a new situation — that the real attacker is still at large and can do more harm.”

Berlin attack: Suspect arrested by German police

A spokesperson for Berlin police said he could not confirm the report when contacted by The Independent.

Germany's top prosecutor, Peter Frank, said the massacre could have been carried out by more than one person, adding that the suspect in custody "may not have been the perpetrator or belong to the group of perpetrators"

Berlin police chief Klaus Kandt said investigators were "uncertain" of whether they had detained the correct suspect, while the city's police sent out a tweet warning Germans they should stay "alert".

Police presence has been increased at Christmas markets across Germany and officers have been given machine guns and protective vests.

Security sources told local media he was not previously known to intelligence agencies as a potential Islamist.

According to German news agency dpa, blood-smeared clothing was found in the lorry, but no clothing stained with blood was found on the suspect.

When the 23-year-old was arrested he is not thought to have had a weapon with him, German daily Tagesspiegel reported.

Holger Münch, the head of federal crime office joined other officials in expressing doubts about the suspect, saying: “Currently we have one suspect but we are not sure whether he is the perpetrator and we don’t know whether there is only one.

"We have not found the weapon and that leads us to being in a high state of alert. Our investigations are ongoing to see whether there are other perpetrators that we need to arrest.”

In the early hours of the morning, hundreds of armed police raided Germany’s largest migrant accommodation centre at the disused Flughafen Tempelhof airport, where the initial suspect had reportedly been registered.

Germany’s anti-migration Alternative für Deutschland (AfD) party swiftly moved to capitalise on the massacre, blaming Angela Merkel’s decision to open borders to refugees during the height of the crisis in 2015.

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

The lorry attack and a previous suicide bombing and axe attack carried out by asylum seekers are expected to damage Ms Merkel’s bid to be re-elected for a fourth term as Chancellor in next year’s federal elections amid growing anti-migrant sentiment and fear of further atrocities.

The lorry rammed into crowds enjoying the popular Christmas market in Breitscheidplatz at 8.30pm local time (7.30pm) on Monday.

It travelled up to 260ft, killing at least 12 people and wounding 49 more, before coming to a stop. The driver fled and a passenger, a Polish national, was found shot dead in the cabin.

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Police are treating the man as a victim of the terrorist rather than an accomplice, supporting fears raised by the Scania cargo lorry’s owner that it was hijacked.

Authorities have described the massacre as a “probable terror attack” but no group immediately claimed responsibility. Suspicion turned to Isis following two attacks in Germany by its supporters in July, and another lorry ramming that killed more than 80 people in Nice.

There had been no comment on the so-called Islamic State’s propaganda channels by Tuesday morning, suggesting commanders had no prior contact with the attacker. In other “lone wolf” attacks, Isis has waited for online pledges of allegiance or media reports to claim responsibility.

It has repeatedly called for attacks and other European nations supporting air strikes by the US-led coalition against its territories in Syria and Iraq, issuing calls in propaganda videos and detailed instructions for attacks against “Crusaders” online.

The latest atrocity has plunged Germany into mourning, with the interior minister ordering flags to be flown at half mast as a sign of respect. Tributes were being left at along police cordons near the scene and a book of condolence was opened at a church near the scene of the attack.