Federal prosecutors say the four suspects, who went on trial in Munich on Wednesday, first met with a larger group to in November 2014 to discuss the "the manufacturing of explosives, as well as attacks on Salafists and asylum seekers" in the eastern German city of Leipzig.

By May 2015, when the four defendants were arrested, they had already made a concrete plot "for a bomb attack at an inhabited refugee shelter," authorities said ahead the trial.

"They discussed wrapping the explosives with nails or encasing them in fuel. But the attacks did not take place as they were arrested on May 6, 2015, and have since been in detention," said authorities.

Suspects Markus W., 40, and Denise Vanessa G., 23, allegedly had the task of buying explosives in the Czech Republic, while Markus and a third suspect, Andreas H., 57, were also working on how to make the simple pyrotechnics more powerful. Olaf O., the 47-year-old fourth suspect, is said to have been the "press spokesman" for the group.

Rise in violence

Preliminary figures, collected by the German interior ministry and then published in February by Left party politician Petra Pau, showed that right-wing violence in Germany almost doubled in 2015, compared to 2014. Authorities registered a total of 13,846 relevant offenses in the past year - up 3,305 on 2014's provisional reporting.

Most of these violent offenses - 612 in total - were deemed xenophobic. This figure jumped from 316 xenophobic attacks in 2014. The number of people injured as a result of xenophobic assaults also rose from 272 to 459 between 2014 and 2015.

A new investigative report, published in March, also found that German police and prosecutors are struggling to solve crimes against refugees. Reporters from the journalist collective "Correctiv" and "Der Spiegel" magazine examined the 199 crimes against refugees officially reported in 2014, and found only 15 convictions of the 157 from which they were able to draw conclusions.

The statistics for 2015 are likely to be higher - since the number of crimes reported last year rapidly increased as the influx of refugees grew - but the report said it concentrated on the 2014 figures to allow time for the investigations to run their course.