BERLIN - German authorities said on Wednesday they had uncovered a network of far-right activists in prisons communicating by secret code.
Among the names on the network's address list was that of a woman who goes on trial next week accused of a series of racially motivated murders.
Wednesday's revelations are embarrassing for Germany, which has been shaken by charges that for decades its intelligence services bungled the monitoring of far-right groups.
The justice minister in the state of Hesse, Joerg-Uwe Hahn, demanded a thorough investigation and confirmed inmates' cells had been searched and letters checked in the last few weeks.
"We don't want to repeat the mistakes made by security authorities in relation to the crimes of the (neo-Nazi cell) the National Socialist Underground (NSU)," Hahn told Bild daily.
"We know that far-right criminals are trying to build up networks and new organizational structures from prisons. We will stop this," he added.