WNSL is to respond to the criticisms by replacing some board members with figures from the business world to provide private sector expertise. At present, the board is drawn from the project's interested bodies, including members of the Football Association and the English National Stadium Trust.
The report, drawn up by independent consultant David James and commissioned by WNSL, has been seen as a public relations blow. The board will decide later this month whether to make its findings public.
WNSL chairman Sir Rodney Walker commissioned the report after allegations last year that WNSL had not followed best procurement practice.
The company originally selected a Bovis Lend Lease/Multiplex joint venture to construct the stadium, but negotiations broke down over costs. Multiplex then approached the clients independently with a cheaper scheme.
The James report is understood to consider WNSL's appointment of Multiplex for the project in September 2000 as a mistake because public sector procurement guidelines called for the scheme to be retendered.
The report has caused enough concern for the NAO to consider launching an inquiry
Jowell confirmed in a statement to the House of Commons last month that the report clears WNSL and Multiplex of any impropriety. WNSL did not believe that it had to retender because the project was essentially in the private sector.
The report has caused enough concern at independent parliamentary watchdog the National Audit Office for it to consider launching an inquiry. An NAO spokesman said: "We're considering the nature and scope of the examination to be carried out."
In a further blow, WNSL may be forced to submit a new planning application, which could delay the project by up to four months.
The design by architect Foster and Partners has been modified to cut costs by removing hotel and office elements. Foster director Ken Shuttleworth said: "There needs to be revisions to the existing planning permission."