The police arrested a 28-year-old Syrian in Hamburg on Tuesday on suspicion of planning an attack with an Islamist background. His four-year-old brother, who lives in Kempten in the Allgäu, is said to have helped with the planning, according to the Federal Criminal Police Office, the State Criminal Police Office and the Hamburg Public Prosecutor's Office.

According to the information, the two brothers planned an attack on civilian targets with a self-made explosive belt. The 28-year-old is the main suspect. For a few weeks he had purchased raw materials for the production of explosive material via the online platform Ebay and other providers. His brother in Kempten encouraged him to plan the crime.

An arrest warrant from the district court of Hamburg had already been issued against the 28-year-old for terrorist financing. Several objects in Hamburg and in Kempten were searched on Tuesday morning. Extensive evidence, including chemical substances, was secured. 250 police officers were involved in the operation.