A man has caused a series of motorway accidents in Berlin injuring six people, including three seriously, in what German prosecutors Wednesday described as a suspected Islamist attack.

Police said the man caused three accidents on the Autobahn 100 in the Tempelhof-Schoeneberg district shortly before seven pm (1700 GMT) on Tuesday, before claiming that a box in his car contained a "dangerous object".

The 30-year-old Iraqi had targeted motorcyclists in particular in a "quasi hunt", a spokesman for the prosecution told a press conference.

Local media reported that the man had shouted "Allahu Akbar" (God is Greatest) when he emerged from his mangled black Opel Astra.

The mangled black Opel Astra on Berlin's Autobahn 100 after its driver caused three accidents
The mangled black Opel Astra on Berlin's Autobahn 100 after its driver caused three accidents AFP / Odd ANDERSEN

"The possibility of an Islamist attack cannot be ruled out," prosecutors said in a statement.

"Statements by the accused suggest a religious Islamist motivation" for his actions. "There are also indications of psychological instability", they added.

The suspect was arrested on suspicion of attempted murder in at least three cases and later today was to face a judge who will decide whether he should be placed in a psychiatric facility.

One of the injured was a firefighter, said Berlin interior minister Andreas Geisel, adding that he was "dismayed that innocent people have fallen victim to a crime out of nowhere".

"We must be aware that Berlin remains a focus of Islamist terrorism," he added.

The scene after a man caused a series of motorway accidents in Berlin
The scene after a man caused a series of motorway accidents in Berlin AFPTV / Odd ANDERSEN

German media reported that a motorcyclist was also among the injured.

The suspect had published clues on social media that he was planning an attack, according to the DPA news agency.

He had posted photos of the car used for the attack on Facebook, along with religious slogans, the report said, citing a spokesman for the prosecution.

The driver had "targeted motorcyclists in particular", prosecutors said
The driver had "targeted motorcyclists in particular", prosecutors said AFP / Odd ANDERSEN

"Nobody come any closer or you will all die," the Bild newspaper quoted the suspect as saying after he got out of his car and placed the metal box on the roof.

His vehicle was apparently brought to a halt after crashing into a motorbike.

However, when police opened the box using high-pressure water jets it was found to contain nothing but tools.

The motorway was closed for several hours, causing significant traffic jams with drivers asked to leave their vehicles as a precaution.

Investigators have not found any links to a terrorist organisation so far, prosecutors said.

People with ties to Islamic extremism have committed several violent attacks in Germany.

The deadliest was a truck rampage at a Berlin Christmas market in December 2016 that killed 12 people.

The Tunisian attacker, a failed asylum seeker, was a supporter of the Islamic State jihadist group.

More recently, an Islamist and his wife were convicted of planning a biological bomb attack in Germany in 2018 with the deadly poison ricin.

The pair had ordered castor seeds, explosives and metal ball bearings on the internet to build the toxic bomb.

The man was sentenced in March to 10 years in prison while his wife received an eight-year sentence in June.

Since 2013, the number of Islamists considered dangerous in Germany has increased fivefold to 680, according to security services.