David Calvert-Smith QC threatened to sack the "tens" of lawyers in the Crown Prosecution Service (CPS) who he believed were beyond reform.
As part of a drive to restore confidence in the CPS, Mr Calvert-Smith pledged to root out, from the 2,000 the service employs, failing lawyers who spend too much time on paperwork instead of trying to secure prosecutions.
"This tiny minority consistently fails to give the service to the public which the public expects and is entitled to," said Mr Calvert-Smith, who took over as head of the CPS in November.
He added: "The number of people who are beyond redemption, that no amount of training or encouragement can save, is certainly in tens - I know a few.
"If they are not up to the job, they've got to go."
He criticised the pay gap between lawyers who appear for the defence and those for the prosecution. Defence counsel get 83 per cent more on average than their prosecution counterparts.
The DPP is particularly concerned with getting top quality lawyers to represent the CPS in middle-ranking cases, such as rape trials, which have a notoriously low success rate. In murder cases, the CPS usually hires a leading barrister.
Mr Calvert-Smith said the Government was looking at this problem and would address it, although he argued that defence barristers were often significantly better than their prosecution counterparts.
Mr Calvert-Smith took the job after Dame Barbara Mills resigned as DPP following the damning Glidewell Report into the service last year which said that 5,400 acquittals in 1997 were due to "matters well within the control of the CPS".
There will be a shake-up in the CPS this month with 42 new chief crown prosecutors, who will act like American district attorneys, responsible for their own geographical areas, which are based on the existing police force boundaries.
Mr Calvert-Smith told BBC Radio yesterday: "The vast majority of staff in the CPS work extremely hard for not very good salaries and do the job exceptionally well.
"I don't want anybody in my employment to think I have a grudge against the workforce. Nothing could be further from the truth."
Despite the vote of confidence in his workforce, the DPP has said he is disappointed by the standard of applicants from outside the CPS.
The new chief crown prosecutors will be all-powerful in their new areas with responsibility for prosecution decisions and a higher public profile. Mr Calvert-Smith, 53, is disappointed that only 10 women and one black lawyer have been appointed to the new posts.
Dame Barbara Mills' early retirement came after complaints that she was identified with a bureaucratic and demoralised service.