A “SOLDIER of the Islamic State” who carried out the bloody attack on a Berlin Christmas market is still at large after police released their only suspect.

A 23-year-old Pakistani asylum seeker known only as “Naved B” was taken into custody after the deadly attack that killed 12 and injured up to 50 people on Monday evening when a truck ploughed into festive shoppers.

The man was captured in a park after reportedly fleeing the scene, but denied any involvement in the attack. Police now say they have insufficient evidence to form a case against him.

The apparent mix-up comes as terror outfit Islamic State has claimed responsibility for the attack via its Aamaq Agency outlet.

The extremist group said the attack was a “soldier of the Islamic State” who acted in response to calls to target citizens of the coalition combating the organisation.

Earlier Tuesday, the cops had admitted they were unsure whether the 23-year-old in custody was responsible for the attack, or whether he was part of a wider group. At a press conference, Berlin’s Police Chief Klaus Kandt said “it is indeed uncertain he was the driver” of the truck that smashed through market stalls.

Police were waiting on the results of DNA tests from inside the cab of the truck and gunpowder residue from the scene. In the meantime, they were asking people to remain vigilant amid a high-level security threat.

Officials said test results were due Tuesday evening but “we have not come to a firm conclusion yet”.

“We need to consider that we might not have the right person but we’ll need to wait for some early results,” officials said.

The admission came after German newspaper Die Welt reported a senior police source as saying: “We have the wrong man”.

“And thus a new situation. For the real culprit is still armed at large and can cause new damage,” the source said.

German Interior Minister Thomas de Maiziere said the man taken into custody “comes from Pakistan”. He denied being involved in the event and it’s thought he arrived in the country between December 31, 2015, and February 2016 via the Balkans route.

He was reportedly arrested 2.5km from the market. Eyewitnesses report seeing a man flee the cab of the truck, pulling off a mask as he ran.

TRUCK COMPUTER PROVIDES CLUES

The chaos comes as police scour the on-board computer of the truck for clues as to what happened in the hours before it ploughed into crowds.

Berlin police have confirmed the man found dead in the truck was not in control of it when it drove into the festive Breitscheidplatz markets. He has been named by as 37-year-old father of one Lukasz Urban .

It’s believed the truck was hijacked at a depot before being driven into the market about four hours later.

The on-board computer shows at 3.44pm on Monday someone tried to start it before another attempt at 4.52pm. By 5.37pm the truck’s engine was turned over again suggesting that someone unfamiliar may have been attempting to drive it.

By 7.34pm it began to move before driving into crowds at 8.15pm.

The on-board computer on the lorry involved in the Berlin attack reveals more about events prior to the attack https://t.co/ErX5LfVsUB — Sky News (@SkyNews) December 20, 2016

‘FIRST HOT LEAD’

An elite unit of armed police stormed disused Tempelhof Airport at 4am on Tuesday morning.

The site, which was built by the Nazis in the 1930s, was closed years ago and has been converted to temporary accommodation for nearly 2000 refugees. Germany has accepted an estimated 1 million refugees since the 2015 crisis after Chancellor Angela Merkel welcomed Syrian refugees into the country.

On Tuesday, Ms Merkel said she was “shocked” at the attack, which appeared to be Islamist terror, as far-right leaders warned “the horror has arrived” in Germany.

Berlin police said the truck attack at Breitscheidplatz was deliberate and said they are working at “full steam” to find those behind it. German television station N24 said the airport site provides the “first hot lead” after the attack. It’s believed no arrests were made.

“The man who was found dead in the truck did not control the truck,” police said on Twitter.

“Our investigators assume that the truck was deliberately steered into the crowd at the Christmas market at Breitscheidplatz.”

“All police measures related to the suspected terrorist attack at Breitscheidplatz are progressing at full steam and with the necessary diligence.”

Onlookers were terrified on Monday evening when the large truck drove straight through stalls at the festive markets, which were filled with locals and tourists drinking mulled wine and watching the Christmas lights.

The truck used in the carnage had Polish licence plates and the owner of the company claimed it was hijacked.

“We haven’t heard from him since this afternoon. We don’t know what happened to him,” Ariel Zurawski said about the driver.

“He’s my cousin; I’ve known him since I was a kid. I can vouch for him.”

Australian woman Trisha O’Neill said she was at the market with friends when she saw “blood and bodies everywhere”.

“I just saw this huge black truck speeding through the markets crushing so many people and then all the lights went out and everything was destroyed,” she told the ABC.

“I could hear screaming and then we all froze.” Ms O’Neill, who moved to Germany in September, burst into tears when she saw how many people, including children, were laying on the ground.

“I never thought I would see something like this in my life,” she said.

AUTHORITIES CRITICISED OVER MARKET SECURITY

Christmas markets across Europe have boosted security measures as it has emerged Germany’s Interior Minister Bruno Le Roux was only last week briefed on measures to prevent exactly the kind of attack that struck in Berlin.

Concrete bollards — upright posts used to block entrances to streets — had reportedly been recommended to be placed outside Christmas markets. The barriers are common across Europe, particularly in France.

In England, concrete bollards had been installed at a number of locations in recent weeks ahead of similar pop-up markets opening as part of a series of safety measures to protect Christmas market patrons.

Berlin police have denied that lax security in the area allowed the attack, and the city’s police chief expressed doubt concrete barriers would have prevented the attack.

“There are an almost unlimited number of soft targets, that’s simply the fact, so there are many possibilities to kill people with a truck,” Klaus Kandt said at a press conference.

“Putting up concrete blocks would not completely eliminate the risk.”

Mr Le Roux left it up to local authorities whether to raise security after Monday’s night’s attack.

Armed patrols have been introduced at markets in the eastern state of Thuringia and Potsdam, and massive concrete block erected around the markets’ borders.

MARKETS ‘SHOULD HAVE BEEN SHUT DOWN’

One security expert has controversially pinned the blame on German authorities who he says should have done more to “keep people safe”.

In an interview with Sky News, Anthony Glees of Buckingham University said if police had any intelligence pointing to a possible attack on one of the festive meeting places, all Christmas markets should have been closed down.

Referring to a US State Department warning issued in November telling citizens to exercise caution at “holiday festivals, events and outdoor markets”, Professor Glees said if German authorities had similar intelligence, they should have done more.

“Forgive me for saying this on such a tragic evening, it is mealy-mouthed to tell individual citizens to be careful when they go to Christmas markets. It is the job of the state and agencies of the state, the intelligence of security agencies to keep people safe,” he said.

“If there was clear intelligence that a Christmas market was gong to be attacked, then all Christmas markets should have been shut until that danger was dealt with.

“You cannot tell people to watch out for a truck that might be driven by terrorists in their direction. You cannot do it that way.”

AUSTRALIANS SHOULD HAVE ‘EXIT PLAN’

Foreign Minister Julie Bishop has warned Australians abroad to have an “exit plan” when visiting Christmas markets and other mass gatherings, in case of a terror attack.

“We ask people to take care, to take the normal precautions but if they are visiting places like a Christmas market to ensure that they have an exit plan worked out should there be a security incident of this type or worse,” she told the Nine Network in an interview Wednesday morning.

Ms Bishop said the attack in Berlin had all the hallmarks of a terror event, although German authorities were yet to confirm a motive.

“We stand with the German people and the German government in the fight against terrorism,” she said.

Were you there? Email victoria.craw@news.com.au

— With Wires