The family of the suspected Berlin attacker have urged him to give himself up to police amid mounting evidence he was the terrorist behind the massacre.

Anis Amri, a 24-year-old Tunisian man, remains at large three days after a lorry ploughed into a German Christmas market, killing 12 people in injuring at least 50 more.

His fingerprints have reportedly been found on the vehicle’s door, while Amri’s asylum documents were discovered under the lorry’s driver’s seat.

Amri's fingerprints were found on the lorry door (AFP/Getty)

The suspect’s family said he left Tunisia several years ago for Europe and kept in contact with his brothers via Facebook and phone, but they have not heard from him since Monday’s attack.

Abdelkader Amri said his brother may have been radicalised while serving a prison sentence for setting fire to a school in Italy, where he moved to during the 2011 Arab Spring.

“I ask him to turn himself into the police. If it is proved that he is involved, we dissociate ourselves from it,” he told the Associated Press.

Abdelkader said the whole family was “in shock” and struggling to come to terms with the possibility his brother may be behind the massacre.

“If he's guilty, he deserves every condemnation,” he told the AFP news agency. “We reject terrorism and terrorists - we have no dealings with terrorists.”

Amri’s estranged father told a Tunisian radio station his son had a lengthy criminal past, being sentenced in absentia to five years in prison for aggravated robbery in his hometown of Oueslatia.

Isis has gained a foothold in Tunisia, where its supporters have launched attacks at the Bardo Museum and at a beach in Sousse, where a gunman murdered 38 mostly British tourists.

The terrorist group is known to target young criminals with propaganda offering redemption through jihad, in what analysts call an emerging “crime-terror nexus”.

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

Amri arrived in Germany in July 2015 but his application for asylum was rejected in June, when authorities were unable to deport him because Tunisia had no proof of his nationality.

The necessary paperwork did not arrive until Wednesday.

Anger at security services was growing after it emerged Amri was known to be a terror threat and had been investigated over a previous plot, but not arrested.

Prosecutors launched a probe into claims Amri was planning a break-in to finance buying automatic weapons for an attack, but surveillance that started in March failed to reveal evidence of a terror plot and was stopped in September.

Separate probes into extremist preachers operating in Germany showed Amri had offered himself a as a suicide bomber, Der Spiegel reported, but the wording of the messages was not deemed conclusive enough to warrant an arrest.

He also raised a red flag for counter-terror agencies in the US, which put Amri on a no-fly list after finding he had conducted online research into making improvised explosive devices and communicated with Isis members on the Telegram messaging app.

Islamic State claims responsibility for Berlin truck attack

Stephan Mayer, a politician from the CSU party, said the new suspect had ties to a network of Islamic extremists, reported to include a hate preacher known as Abu Walaa, who was arrested as part of a cell of Isis supporters sending militants to Syria earlier this year.

Amri was also said to have followed an extremist preacher known as Boban S, who was arrested in Dortmund on suspicion of supporting Isis in November.

A house was raided in the city early this morning, according to local reports, and police have also searched Amri’s former accommodation in Emmerich, North Rhine-Westphalia.

A European arrest warrant issued for the suspect gives six different aliases, showing Amri going under different names, birth dates and even nationalities.

The technique has previously been used by Isis militants including the Paris and Brussels attackers in attempts to throw authorities off their scent.

Prosecutors are offering a €100,000 (£85,000) reward for information leading to Amri's arrest, warning people not to approach the “violent and armed” suspect.

Isis has claimed responsibility for the Berlin massacre, calling the perpetrator a “soldier of the Islamic State” who was obeying calls to attack supporters of the US-led coalition launching air strikes on its territories in Syria and Iraq.