German authorities have questioned whether Berlin market truck attack suspect acted alone as the manhunt continues for Tunisian-born Anis Amri.

Germany’s top prosecutor Peter Frank said the attack was reminiscent of July’s deadly truck rampage in Nice, France, and appeared to follow instructions published by IS.

“We don’t know for sure whether it was one or several perpetrators,” he said.

“We don’t know for sure whether he, or they, had support.”

It’s been revealed that Amri’s fingerprints were found inside the truck that ploughed into a Christmas market, killing 12 people.

Germany’s Interior Minister Thomas de Maiziere said that discovery meant that the suspect is in high probability the perpetrator.

A Europe-wide search has been launched for Amri, who was known to security agencies and had links to Islamist militants.

A 100,000 euro reward has been offered for information on the 24 year old, who arrived in Germany via Italy last year and applied for asylum.

That application was turned down because authorities believed he was planning an atrocity and was in contact with high level Islamists.

Amri allegedly researched how to build explosive devices online and communicated with the Islamic State, the New York Times reported.

The wanted photo issued by German police of Anis Amri.

He had communicated with IS at least once and was also on a US no-fly list, the newspaper said, citing a US official who spoke on condition of anonymity.

IS has has claimed responsibility for the attack.

Jailed in Italy

Berlin Christmas market attack suspect, Anis Amri, served four years’ prison in Italy, according to German media reports.

The Berliner Zeitung has reported that Amri came to Italy as a refugee in 2011 and was housed in a detention centre for minors, where he committed “various criminal acts” and “wilful damage to property”.

Italy’s La Stampa newspaper reported that Amri had also committed arson at the detention centre, was charged and sentenced as an adult to four years in prison.

After difficulties with Tunisian authorities in deporting him, Amri managed to slip out of Italy and into Germany.

Meanwhile, German police have raided two addresses in the hunt for Amri which yielded no sign of the suspect.

AAP also reported that Tunisia’s anti-terrorism police have raided the house of Amri’s family, Tunisian online newspaper al-Chorouk reports.

Amri’s family reportedly confirmed that his contacts with them have not been regular since he left the country during the late 2010 uprising, the report adds.

The 24-year-old suspect belongs to a poor family in Tunisia’s province of Kairouan, it says.

Berlin carries on

Berlin Mayor Michael Mueller said it was “good to see that Berliners aren’t being intimidated”.

“I don’t think there’s any need to be afraid,” he told ZDF television.

“The police presence has been significantly heightened … and of course other measures taken to find the perpetrator quickly.”

Mr Mueller argued that there are limits to increasing security, given the number of public spaces and events.

“It wouldn’t be our free and open life any more if we escalated security measures so much that people worry about going anywhere, that there are strict entry checks,” he said.

“We don’t want that. It must be appropriate and goal-oriented.”

Referring to security measures, he added: “A lot has happened, and more certainly will.”

German police are searching hospitals for him after reports DNA retrieved from the truck was used to trace the attacker to hospitals.

Other local media, Allgemeine Zeitung and Der Spiegel, claimed police traced him from an identity document was found in the truck.

The document was in the name of ‘Anis A.’, born in Tunisia in 1992.

Police believe the attacker to be injured because the driver whose truck he hijacked was found shot and stabbed to death after the attacker fled the scene and vanished on foot.

Polish driver tried to stop attack

That dead driver has been confirmed as Polish national Lukasz Urban. German media reported Mr Urban may have tried to grab the wheel and steer the attacker away from crowds.

Earlier, Islamic State (IS) claimed responsibility for the attack via its news service. However any concrete evidence the attacker was IS inspired is yet to emerge.

“The executor of the operation in Berlin is a soldier of the Islamic State and he executed the operation in response to calls to target nationals of the coalition countries,” The IS Amaq news agency announced.

Ms Merkel, under pressure for her migrant policy in the wake of the attack, arrives at the market. Photo: Maurizio Gambarini/via AP

On Tuesday evening German Chancellor Angela Merkel said the world “must assume it [the incident] was a terror attack”.

The attack happened at 8am Monday (local time) when a truck was “deliberately driven into a crowd of people working at and shopping at a Christmas market in Berlin’s Breitscheidplatz.

– Wire services