Germany pledges to flush out neo-Nazi prison network

German authorities vowed Thursday to root out a just-discovered neo-Nazi network in the country's prisons that attempted to establish contact with criminals and militants still at large.

The far-right gang in the western state of Hesse used secret code to seek out potential allies beyond the prison walls including a woman set to go on trial next week for her alleged role in 10 murders.

"I have to assume that the communication crossed state lines," Hesse justice minister Joerg-Uwe Hahn told German radio when asked if he believed contacts were established with radicals in the other 15 federal states.

"A number of prisons in nearly all the states and justice ministers from nearly all the political parties have been approached about this" with the aim of determining the scope of the contacts and cutting them off, he added.

A press report this week blew the lid off the prison gang that sent letters and classified advertisements using neo-Nazi codes and symbols in order to establish communication with other militants.

It is thought dozens of inmates at at least three prisons were involved in the ring.

Authorities said they aimed among other things to drum up financial support for convicted felons from the right-wing extremist scene and their families and to recruit and indoctrinate inmates.

They have carried out searches at prisons throughout the state, Hahn said.

At least one letter went out to a prison in a neighbouring state intended for Beate Zschaepe, an alleged member of a far-right killer cell known as the National Socialist Underground (NSU) who will stand trial from Wednesday.

Authorities said there is no evidence to show she received the letter.

"We do not want to repeat the mistakes of the security forces in connection with the NSU crimes again in the penal system," Hahn said, referring to a catastrophic series of missteps in the investigations of the 10 killings between 2000 and 2007.

Justice ministers in states including Berlin and Schleswig-Holstein in the north which has an active far-right scene said they were investigating possible leads.