"I simply don't believe these numbers. How on earth is it measuring this?" said David Rippon, chairman of the British Computer Society's Elite group.
He accused the BSA of manufacturing statistics to scare users into thinking the issue is more widespread than it really is and encouraging them to buy more licences to cover their backs.
"It is engineering an overspend by UK PLC because the products are so difficult to manage. Suppliers need to listen to users' grievances about how hard it is to manage their software," Rippon said.
He urged the BSA to submit its research methods to an independent auditing body to be assessed.
Corporate IT forum Tif chief executive David Roberts said, "[The BSA is] being grossly unrealistic and unprofessional. All it is doing is increasing the divide between suppliers and users."
The BSA said the survey shows a 1% increase for 2002 - the first since 1994 - on 2001's figures. Richard Saunders, a member of the BSA's UK committee, admitted the 1% rise "doesn't have any huge significance".
The study, conducted by International Planning and Research, was based on sales data and market information for 26 business software applications.