Market attack 'terrorist act likely by asylum seeker'

German Chancellor Angela Merkel said on Tuesday that authorities believe a deadly rampage by a lorry driver at a Berlin Christmas market was a "terrorist" attack likely committed by an asylum seeker.

"According to what we know, we have to assume this was a terrorist attack," Merkel, visibly moved and dressed in black, told reporters.

"I know it will be especially hard for us to take if it is confirmed that the person who committed this attack sought protection and asylum in Germany."

Merkel added that if it is confirmed that the suspect, who was detained after the lorry he was allegedly driving killed 12 people in a large crowd, was an asylum seeker, it would be "particularly sickening in relation to the many, many Germans who are involved every day in helping refugees".

She added it would also be repugnant "toward the many people who need our protection every day and who are working on integration in our country".

Media reports said the suspect had arrived in Germany from Afghanistan or Pakistan earlier this year seeking asylum.

Merkel said she personally was "horrified, shocked and deeply saddened" by the attack and would visit the site later Tuesday with her interior minister, Thomas de Maiziere, and Berlin Mayor Michael Mueller.

She pledged that German authorities would "get to the bottom" of the assault and that it would be "punished with the full force of our law".

The arrival of 890,000 asylum seekers last year has polarised Germany, with critics calling the influx a serious security threat. Another 300,000 people have arrived this year.

Merkel still enjoys strong popularity despite her liberal asylum policy but has seen some of her support eroded by the right-wing populist Alternative for Germany (AfD) party ahead of a general election expected next September.

In the immediate aftermath of the attack, AfD leaders blamed Merkel's liberal asylum policy for the carnage.  

Germany's interior ministry said on Tuesday that the truck ramming through a Berlin crowd, killing 12, was an "attack" but that there was no reason to close the country's popular Christmas markets.

After a telephone conference between Interior Minister Thomas de Maiziere and his regional counterparts, the ministry said they agreed "that Christmas markets and other big events should continue to take place".

Calling the incident that left almost 50 others injured an "attack", the ministry said in a statement that "regardless of what we may learn about the exact motives of the assailant, we must not let our free way of life to be taken from us."