Three lawyers for the sole surviving suspect in Germany's biggest neo-Nazi murder trial have asked the court for permission to resign.

The three court-appointed attorneys have been defending Beate Zschaepe since the start of her trial in May 2012 for alleged complicity in the murder of 10 people, most of them immigrants, between 2000 and 2007.

Prosecutors allege that she was part of a group calling itself National Socialist Underground, whose other two members died in 2011.

German news agency dpa quoted one of the lawyers, Wolfgang Heer, as saying Monday that if the court approves their resignation, the trial against Zschaepe will likely have to start over.

Revelations about the authorities' bungling of the case have caused deep embarrassment in Germany, as well as accusations of deliberate cover ups.