The suspects – named as Azizjon B., Muhammadali G., Farhodshoh K., Sunatullokh K. and Ravsan B. – are accused of joining Isis in January 2019 and initially planning to carry out attacks in Tajikistan.

The five men had been planning to attack targets, including US airbases and had already ordered bomb parts online, as well as stocking up on firearms and ammunition.

They also planned an assassination attempt on a person they believed had expressed Islam-critical views in public, and had already begun spying on the intended victim, prosecutors said.

Two of the suspects are also accused of travelling to Albania to carry out an assassination attempt in exchange for US$40,000. However, the project failed and they returned to Germany.

In June 2018, German police said they foiled what would have been the first biological attack with the arrest of a Tunisian suspected Isis supporter in possession of the deadly poison ricin and bomb-making material.

More recently, police in the western city of Offenbach arrested three men in November 2019 for allegedly planning a bomb attack in the name of Isis.

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, some 680 of whom are deemed particularly dangerous and capable of using violence – a five-fold increase since 2013.

Germany remains a target for jihadist groups, in particular because of its involvement in the coalition fighting Isis in Iraq and Syria, and its deployment in Afghanistan since 2001.

Chancellor Angela Merkel has allowed in more than one million asylum seekers since 2015 – a decision that has driven the rise of the far-right Alternative for Germany (AfD) party, which charges that the influx spells a heightened security risk.