Police in Berlin are offering a reward of €100,000 (US$104,260) for information leading to the arrest of the man suspected of involvement in Monday’s attack on a Christmas market which left 12 dead and 48 injured.

LIVE UPDATES: Berlin Christmas market attack

A search is currently underway for 24-year-old Tunisian Anis Amri, who could be armed and dangerous, according to a statement from the Federal Prosecutor's Office (GBA).

"Anis AMRI is 178cm tall and weighs about 75kg, has black hair and brown eyes.” according to the statement.

Police raided two apartments in the Kreuzberg neighborhood of the city but failed to locate Amri. Investigators told Die Welt they believed he had been in one of the apartments before they arrived.

Speaking on Tunisian radio, Amri’s father said he left Tunisia seven years ago as an illegal immigrant and spent time in prison in Italy on accusations of burning a school, according to Reuters.

Amri was also suspected of being involved in a violent robbery in Tunisia, according to his father, who the radio station said is being questioned over possible links between his son and Islamic State (IS, formerly ISIS/ISIL).

Monday’s attack in Berlin saw a Polish-registered truck driven into a crowd in an attack echoing the Nice massacre of July when 86 people were killed.

Identity documents belonging to Amri were reportedly found inside the truck, according to Der Spiegel.

Suspect tracked by authorities for months, surveillance called off in September

German authorities had been tracking the main suspect in the Berlin attack for months before calling off surveillance operations on the 24-year-old Tunisian, Anis Amri.

Amri arrived in Germany in July 2015, at the height of the refugee influx, after serving a four-year prison term in Italy, Ralf Jaeger, the interior minister of North Rhine-Westphalia said, according to AP.

Since February this year the Tunisian was able to move freely around Germany, after registering near the Dutch border. All that time, Amri had been living mostly in Berlin, Jaeger noted.

The main suspect in the attack had been added to a list of potentially violent Islamic extremists. Prosecutors in Berlin even launched an investigation into the potential threat posed by Amri on March 14 following a tip from federal security agencies.

The tip warned that the Tunisian might be planning a possible future attack and had been seeking to purchase automatic weapons. After conducting surveillance for several months, German authorities failed to find evidence to substantiate the claim, calling off surveillance on Amri in September.

"Security agencies exchanged information about this person in the joint counter-terrorism center, the last time in November," said Jaeger.

READ MORE: Berlin market attack: Police searching for Tunisian man after finding ID in truck – reports

Jaeger also revealed that the suspect's asylum application had been rejected in July, but authorities failed to deport him because the 24-year old didn't have valid identity papers. In August migration authorities made an effort to help Amri secure a replacement passport.

"Tunisia at first denied that this person was its citizen, and the papers weren't issued for a long time," Jaeger said."They arrived today."