Germany says Tunisian's fingerprints found in Christmas market crash truck

• Trump after Berlin, Turkey attacks: 'I've been proven to be right'
• Truck plows into crowd at Berlin Christmas market, 12 dead
• Germany police hunt Tunisian asylum-seeker over Christmas market attack
• Germany frees suspect in market attack, says perpetrator maybe still at large

A hunt is underway across Europe for Anis Amri, 24, as Germany reels from its worst attack in decades.

A video clip from a car-mounted dashcam obtained exclusively by Reuters appears to show the truck driving into the market at speed, immediately after which people run away from the scene.

Police patrol at the re-opened Christmas market at Breitscheid square in Berlin, Germany, December 22, 2016, following an attack by a truck which ploughed through a crowd at the market on Monday night. REUTERS/Fabrizio Bensch

"We can report today that we have new information that the suspect is with high probability really the perpetrator," Interior Minister Thomas de Maiziere told reporters on Thursday.

"In the cab, in the driving cabin, fingerprints were found and there is additional evidence that supports this," he said.

Frauke Koehler, a spokeswoman for the federal prosecutor's office, told reporters: "At this point in the investigation, we assume Anis Amri drove the truck."

Police had carried out searches across Germany on Thursday but made no arrests, she said.

Chancellor Angela Merkel, facing demands to take a much tougher line on immigration and security, said she hoped the perpetrator would be arrested soon.

Islamic State has claimed responsibility for the attack, in which the truck mowed through a crowd of people and bulldozed wooden huts selling Christmas gifts and snacks beside a famous church in west Berlin.

One of the 12 dead was the Polish driver from whom the truck had been hijacked. His body, stabbed and shot, was found in the cab.

Amri had been identified by security agencies as a potential threat and rejected for asylum, but authorities had not managed to deport him because of missing identity documents.

In Tunisia, two of Amri's brothers, Walid and Abdelkader, said they feared the failed asylum-seeker may have been radicalized by radical Islamists while he spent almost four years behind bars in Italy.

"He doesn't represent us or our family," Abdelkader told Sky News Arabia. "He went into prison with one mentality and when he came out he had a totally different mentality."

The suspected involvement of a migrant - one of more than a million allowed into Germany in the past two years - has intensified political pressure on Merkel, who plans to seek a fourth term in elections next year.

Armin Schuster of her Christian Democratic party told broadcaster NDR: "We need to send the signal: Only set off for Germany if you have a reason for asylum."

Germany had until now been spared the kind of mass-casualty militant attacks that have hit France, Spain and Britain in recent years. No attack on German soil has claimed so many lives since 1980, when 13 people including the suspected bomber, a member of a neo-Nazi group, were killed in an explosion at a Munich beer festival.