Building Capacity in the Third Sector was due to be published in early 2008, but was put back without explanation (14 May, page 1).
Former shadow charities minister Greg Clark wrote to the NAO last month to ask why the report had still not been published.
The reply from Rob Prideaux, a director at the NAO, said it needed extra evidence on the impact of infrastructure programme Capacitybuilders and Futurebuilders. He said the Government had not attempted to delay the report.
"Substantive discussions with the Office of the Third Sector will not take place until the additional fieldwork has been completed and analysed," he said. The report is now due in early 2009.
New shadow charities minister Nick Hurd said a lot of the information in the report would be out of date by the time it was published.