A fourth suspect connected to the foiled bombing of Taylor Swift's Vienna shows last year has been indicted in Germany ... according to reports.

The Associated Press -- citing documents filed in a Berlin court -- reports an individual identified only as Mohammad A. was indicted earlier this month for allegedly helping translate bomb-making instructions in the plot to blow up Ernst Happel Stadium in Austria. He also allegedly set up online contact with members of the Islamic State.

Mohammad A. -- BBC News reports German authorities describe him as a juvenile -- also stands accused of supporting a foreign terrorist organization and preparing a serious act of violence. He is reportedly not in custody. It's unclear why he's been indicted in Germany -- the bombing plot was supposed to go down in neighboring Austria.

Remember ... three people -- an 18-year-old Iraqi citizen, a 19-year-old Austrian citizen and a 17-year-old, also Austrian -- were all arrested last summer. The 17-year-old was released without charges soon afterward, the New York Times reports. The lawyer for the 19-year-old called the charges against him "pure fantasy" in August.

The shows were canceled even after two arrests were made ... with authorities telling us at the time they weren't sure they'd caught all the suspects in the case.