Isis urges German Muslims to commit Brussels-style attacks on airports and federal buildings

Islamic State (Isis) has put Germany in the crosshairs of its propaganda machine with a series of online posts calling on Muslims in the country to subject airports and institutions to Brussels-style attacks. The Cologne-Bonn airport and the German Chancellery building housing Angela Merkel's office were indicated as potential targets by the jihadi group's Furat media agency, which released apocalyptic images depicting the two sites under siege.

One showed the chancellery on fire beside a masked militant and a tank, with the German-language caption "Germany is a battlefield". Another depicted an Isis fighter in camouflage gear standing outside the Cologne-Bonn airport terminal with a message reading "What your brothers in Belgium were able to do, you can do too".

A third urged German Muslims to take up arms against their own country, claiming German warplanes participating in a US led coalition against the Islamist group were killing civilians in Syria. The doctored images were released as anti-terror security services were on high alert across Europe following the suicide bombings that killed 32 people at the Brussels airport and a central Metro station.

Germany's federal police, the BKA, said they were aware of the online threats but no tightening of security was immediately needed. "We are aware of this material and our experts are checking it," a BKA spokeswoman told Reuters. "It is clear that Germany is the focus of international terrorism and that attacks could happen, but this material doesn't change our security assessment."

More than 700 German radicals are believed to have travelled to Iraq and Syria to join Islamist militants in recent years. Berlin joined the anti-IS coalition in Syria with a deploying personnel and equipment in a non-combat role in December last year. Its six Tornado jets involved are used for reconnaissance and refuelling.