Families say ‘Ulm 5’ have been detained under extreme prison conditions since arrest last September

Five pro-Palestinian activists are due to appear in court over an attack on an Israeli arms company in Germany, in proceedings their families say could become a “show trial”.

The Berlin-based activists, who are British, Irish, German and Spanish citizens, have been held in pre-trial detention in separate prisons since 8 September. They are alleged to have broken into Elbit Systems, in the city of Ulm in Baden-Württemberg, in the early hours of 8 September, causing hundreds of thousands of euros of damage before calling the police to arrest them.

The Ulm 5 have been charged with trespass, destruction of property and participation in a criminal organisation under section 129 of the German criminal code. The trial is due to start on Monday.

The section 129 charge means authorities consider the accused a threat to society, allowing them to deny bail. Families of the defendants say they have been locked up for up to 23 hours a day and had access to visits, books, phone calls and mail restricted. If found guilty, they face up to five years in prison.