The BBC's Legal Affairs Correspondent Joshua Rosenberg previews the report on the Radio 4 Today programme

Former Appeal Court judge Sir Iain Glidewell has taken a year to compile his report and it is thought it will be highly critical of senior managerment.

He is also expected to recommend splitting the job of Director of Public Prosecutions in two.

Police see the CPS as interfering

Former DPP Dame Barbara Mills announced her decision to retire early 10 days ago but insisted it was nothing to do with the imminent publication of the report.

Sir Iain is expected to recommend creating a new post of chief executive to take over the administration and running of the service, leaving the DPP to concentrate on the core work of prosecution decisions and policy.

The government has refused to comment on who might be appointed to the post, after speculation that Mark Addison, former private secretary to Baroness Thatcher, might get the job.

The Attorney General, John Morris, has already signalled he will restructure the CPS' existing 13 regions into 42, each one matching a police force area.

Each would be headed by a Chief Crown Prosecutor modelled on the US District Attorney, who would be expected to build up a much closer working relationship with local police.

Jack Straw is looking forward to the report

In the past detectives have been strongly critical of what they saw as a CPS reluctance to prosecute cases which stood a good chance of conviction.

One Police Federation official described it as the Criminals Protection Society.

They have also been critical of its inefficiency, in 1997 the CPS cost £283 million but despite rising crime rates, the number of cases it brought has fallen from 1.5 million to 1.3 million over five years.

Recent initiatives to improve co-operation between the two services have included posting CPS lawyers to police stations full-time to advise officers on successfully taking cases to court.

Home Secretary Jack Straw said recently the Glidewell report would identify "potentially beneficial changes in the way the CPS work with the police and other agencies".

But Sir Iain has also had to tackle the problem of morale among CPS staff.