Germany’s Interior Minister Nancy Faeser said on Monday there are indications that the Saudi suspect in a deadly car-ramming attack on a Christmas market 10 days ago was mentally ill.

Faeser told reporters that no motive had yet been established, but “there are striking signs of a pathological psyche”.

She added that lessons must be learnt on how to track potential “perpetrators who are psychologically disturbed and ... driven by confused conspiracy theories”.

“Such attackers do not fit any threat profile,” she said, warning that security services will need “other indicators and action plans” to deal with them.

Faeser was speaking after answering questions in a closed-door parliamentary committee examining the background to the December 20 attack which left five people dead and wounded more than 200.

People begin to dismantle the closed Christmas market shops at the site of a car-ramming attack. Photo / AFP

Police arrested a Saudi psychiatrist, Taleb al-Abdulmohsen, at the scene.

Faeser said there were “tens of thousands of tweets” Abdulmohsen had sent over the years that were yet to be examined.

“That explains why not everything is on the table yet ... who knew about which clues and what was passed on when must be carefully clarified,” she said.

-Agence France-Presse