German media reported on Tuesday that the head of the German wing of the international neo-Nazi group "Blood and Honour" was scouted in the 1990s by the Germany's federal intelligence agency, the Bundesamt für Verfassungsschutz (BfV), to work as an informant.

The reports suggest that, in exchange, he may have been partly protected by the authorities and shown greater leniency for his crimes.

The investigation, reported by Germany's national television network ARD, prompted Germany's two main opposition parties to call for an explanation over the affair. Left Party lawmaker Andre Hahn said he would address the matter directly with German Interior Minister Thomas de Maiziere. Meanwhile, Green party security policy spokeswoman Irene Mihali told ARD: "If the German head of Blood and Honour worked as an informant, then clearly a line was crossed. The BfV must provide a full explanation to the Bundestag."

The investigation centers on a secret note issued by Berlin state police (LKA) revealing that the head of the German wing of the Blood and Honour group had been suspected of liaising with authorities by other members of the neo-Nazi group. The suspicions stemmed from a criminal trial for a politically motivated attack perpetrated by the alleged informant, where he was only handed a relatively meager 3,000 mark fine (1,500 euros, $1,660) rather than sentenced to prison.

Hahn said that if the revelation proved to be accurate, it would mean that the BfV hadn't been monitoring the group, but "steering it itself."

De Maiziere is expected to discuss the revelations at a meeting on Wednesday with the parliamentary supervisory board for Germany's intelligence services.

Links to NSU

In 2000, the Blood and Honour group was banned in Germany, along with its armed wing known asCombat 18. However, earlier this year German media reported that Combat 18 was once again active in Germany after an investigation found that authorities had received hundred of reports of the militant group's activity over the past four years.

Combat 18 was one of the most influential supporters of the extreme far-right National Socialist Underground (NSU), having provided its members with arms and accommodation.

Germany's Tagesspiegel newspaper reported that the suspected informant testified in the long-running NSU trial in Munich, although his responses allegedly offered little of substance to the case.

dm/gsw (dpa, ARD)