BERLIN (Reuters) - Islamic State posted pictures on the Internet calling on German Muslims to carry out Brussels-style attacks in Germany, singling out Chancellor Angela Merkel’s offices and the Cologne-Bonn airport as targets, the SITE intelligence group reported.

An aerial picture shows the Konrad Adenauer airport of Cologne-Bonn near the North Rhine-Westphalian city of Cologne, Germany May 6, 2015. REUTERS/Wolfgang Rattay

Western Europe is on high security alert after last week’s Islamic State suicide bombings in the Belgian capital that killed 32 people at its airport and in a metro station. On Wednesday, France said it was investigating a man on suspicion of planning an imminent act of “extreme violence”.

The Islamic State images and graphics, widely published by German media on Thursday, included slogans in German inciting Muslims to commit violence against the “enemy of Allah.”

Germany’s BKA federal police, who monitor suspected militants with German passports returning from stints fighting in Syria and Iraq, said it knew of the images but that their publication did not necessitate extra security measures.

“We are aware of this material and our experts are checking it,” a BKA spokeswoman said. “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.”

Federal police chief Holger Muench said after the March 22 attacks in Brussels that Islamic State appeared eager to carry out further “spectacular” attacks in Europe as it was suffering setbacks on battlefields in Iraq and Syria.

One of the disseminated Islamic State images features a militant in combat fatigues standing in a field and gazing at Cologne-Bonn airport with a caption reading: “What your brothers in Belgium were able to do, you can do too.”

Another shows the German chancellery building in Berlin on fire with an Islamic State fighter and a tank standing outside the structure. The headline reads: “Germany is a battlefield.”

Germany joined the U.S.-led air strike campaign against Islamic State in Syria last year, though limiting its role to reconnaissance and refueling missions, after the jihadist group killed 130 people in shooting and bombing attacks in Paris.

A third graphic featured a military jet, which German media identified as a Tornado used by the German air force, against the backdrop of a mountainous area juxtaposed with the bloodied faces of women and children - apparently meant to represent civilians who Islamic State says have been killed by air strikes on areas it controls.

The caption under this image says: “Will you continue to grieve or will you finally act?”

All five pictures circulated on social media on Wednesday bore the logo of Furat Media, an Islamic State affiliate, according to SITE.

German media also published an Islamic State video celebrating the attacks in Brussels that featured a three-second shot of Frankfurt Airport, apparently taken from German television news footage.

The BKA spokeswoman said police were aware of that video as well and current security measures were sufficient.