German police raid Chechen 'Islamists' over attack plot

German police carried out raids on suspected Islamist militants across the country early Tuesday over allegations they were plotting an attack, Berlin officials said.

German authorities are on high alert for Islamist threats to Europe's most populous country, which has in recent years suffered several attacks.

"On suspicion of planning a serious violent act endangering the state, search warrants are being executed in Berlin, Brandenburg, North Rhine-Westphalia and Thuringia," the Berlin attorney general's office said via Twitter.

The alleged militants of Chechen origin are aged between 23 and 28 and "suspected of having scouted locations for a possible Islamist attack", Berlin police said in a statement.

The suspicions were prompted by pictures found on the mobile phone of one of the suspects during a routine police check, it added.

German news magazine Spiegel said the suspects may have had a synagogue in Berlin in their sights after video material of the building was found. The suspects also allegedly scouted out several shopping centres as possible targets, said the magazine.

Some 180 officers took part in the raids, confiscating cash, hard drives and knives. Police would not confirm Der Spiegel's report on possible targets.

But they added that "based on the current information, there was not yet any concrete danger of an attack".

Germany's deadliest attack was a truck rampage at a Berlin Christmas market in December 2016.

The attacker, Tunisian asylum seeker Anis Amri, hijacked a truck and murdered its Polish driver before running over another 11 people.

He was shot dead by Italian police in Milan four days later while on the run. Since then, German authorities have thwarted nine attacks believed to have radical Islamist motives.

Most recently, police in the western city of Offenbach arrested three men in November for allegedly planning a bomb attack in the name of Islamic State.

That same month, a Syrian was arrested in Berlin accused of having procured key components for an explosive device and discussing bomb-making tips with other suspected Islamists in an online chat group.

Germany's security services estimate there are around 11,000 Islamic radicals in Germany. Of them, some 680 are deemed particularly dangerous and capable of using violence -- a five-fold increase since 2013.

Around 150 of these potentially dangerous individuals have been detained for various offences.