An officer in the Federal Office for the Protection of the Constitution (BfV) has been arrested over fears he may have been involved in plotting a terrorist attack on the agency.

The arrest of the 51-year-old officer who works for the domestic security agency — equivalent to the FBI — comes after he made a “partial confession” to fellow agents that he was not just observing the radical Islamist scene in Germany, but had also become a part of it, Der Spiegel reports.

The revelation has stoked new fears that Islamists may have infiltrated the spy agency which German Chancellor Angela Merkel has recently said the German government would drastically expand in the coming year.

According to the confession, he was plotting to bomb the national headquarters of the agency which is located in Cologne.

A spokesman for the BfV said, “He is accused of making Islamist remarks online under a false name, and offering internal information during chats.”

The man had been at the agency for several months starting in April of this year, and was hired to monitor the radical Islamist scene but admitted he had joined the agency in order to infiltrate it and gather information.

Included in the logs of his chats were messages in which he talked to fellow radical Islamists, and tried to recruit them into the domestic spy agency to facilitate attacks against people they referred to as “non believers.”

A former bank clerk, the man was unknown to the agency until he joined, and even his wife was unaware that he had secretly converted to Islam.

His conversion was made via phone call and he pledged an oath to a Salafist Imam named Mohamed Mahmoud who previously preached in Berlin before travelling to Syria to fight for the Islamic state.

The BfV noted that he was “inconspicuous” during his application and all through his training. The agency did note the man’s attention to secrecy as they discovered multiple storage devices which outlined internal operations, assignments and deployments during the course of their investigation.

The spy was finally caught after trying to recruit who he thought was a fellow Islamist into the agency on the internet, but turned out to be a fellow agent at the BfV.

The BfV wields great power to spy on the citizens of Germany, made even stronger by recent reforms by the government of Chancellor Angela Merkel.

The Salafist scene is also growing within the country as many estimate that there are over 9000 adherents of the radical Islamic ideology which has often turned members onto a path of violence and terrorism.