Reward of 100,000 euros offered by Germany for information on Anis Amri, who had previously been under surveillance.

Germany has launched a Europe-wide manhunt for a “violent and armed” Tunisian man, saying that he is a suspect in Monday’s Christmas market attack in Berlin.

A reward of 100,000 euros ($104,260) was offered on Wednesday for information leading to the arrest of the man, who allegedly used at least six names and three nationalities.

The suspect has been named as 24-year-old Anis Amri.

Amri was under covert surveillance for several months this year, German authorities said, but stopped watching him because they were unable to prove their suspicions.

A judicial source said Amri was then suspected of planning a robbery to fund the purchase of automatic weapons, Reuters news agency said.

His identification papers were reportedly discovered in the truck that struck the Berlin market.

“This is a suspect, not necessarily the perpetrator,” Thomas de Maiziere, Germany’s interior minister, said after briefing parliament’s domestic affairs committee.

“We are still investigating in all directions.”

Serious injuries

Twelve people were killed and 48 injured in the Christmas market attack, responsibility for which has been claimed by the Islamic State of Iraq and the Levant (ISIL) group.

Twelve of the wounded were still being treated on Wednesday for very serious injuries and some were in critical condition, health officials in Berlin said.

De Maiziere would not give further details on the suspect, but committee members said Amri had spent time in pre-deportation detention.

Twelve people died on Monday when a truck drove into a Christmas market [EPA]

A German security official said that authorities had considered him a possible threat previously and had been trying to deport him after his asylum application was rejected this summer.

Germany issued a notice to other European countries overnight seeking the arrest of Amri, but initially held off on going public so as not to jeopardise the manhunt.

After German media published photos of Amri and a partial name, federal prosecutors went public with the information.

‘Violent and armed’

Federal prosecutors described Amri as being of average height and weight, with black hair and brown eyes.

“Caution: He could be violent and armed!” the federal prosecutor’s notice warned. “A reward of up to 100,000 euros has been issued for information leading to the suspect’s arrest.”

The suspect apparently arrived in Germany in July 2015 and has lived in three German regions since February, mostly in Berlin, said Ralf Jaeger, interior minister of western North Rhine-Westphalia.

Police in Berlin, meanwhile, said they had received more than 500 tips on the Monday evening attack.

READ MORE: Berlin attack – Community spirit and resilience prevail

Amri fled Tunisia to Italy after the 2011 revolution that overthrew Zine El Abidine Ben Ali, Tunisia’s longtime leader, and spent three years there before travelling on to Germany, a security official told AFP news agency.

Tunisian anti-terrorism police questioned Amri’s family in the North African country, the security source told AFP, adding that the man had been arrested in Tunisia for drug use.

“When I saw the picture of my brother in the media, I couldn’t believe my eyes. I’m in shock, and can’t believe it’s him who committed this crime,” his brother Abdelkader Amri told AFP.

But “if he’s guilty, he deserves every condemnation. We reject terrorism and terrorists – we have no dealings with terrorists”.

Amri’s sister, Najoua, said: “I was the first to see his picture and it came as a total shock. I can’t believe my brother could do such a thing.

“He never made us feel there was anything wrong. We were in touch through Facebook and he was always smiling and cheerful.”

Some politicians have blamed Chancellor Angela Merkel’s open-door migrant policy for making such attacks more likely.

The anti-immigrant Alternative for Germany (AfD), which has gained support in the past two years as Merkel’s popularity has waned, said on Tuesday that Germany is no longer safe.

Joachim Herrmann, Bavarian interior minister, told German radio there was a higher risk of attacks because of the influx of refugees and migrants in the past two years.

Sergey Lagodinsky, a Berlin-based political analyst, told Al Jazeera that Monday’s attack places “great pressure” on Merkel, and that those on the right “will be using and abusing this topic.

“I would assume she will try and move to the right, and speak to the centre,” he said.

“This could be fatal for her if she does not find the right way. Her priority now will be to demonstrate herself as a security chancellor.”