Software piracy rates in the UK remain the second lowest in the world. But, even so, 26% of software in the UK was being used illegally last year, according to the BSA.
Estimates suggest that software piracy in the UK cost the industry £604m last year.
The BSA has called on UK IT managers to make staff sign a guarantee to protect software copyright as part of their terms of employment.
Mike Newton, the BSA's campaign relationship manager in the UK, warned that IT directors are facing increasing risks of employees using the Internet to download pirated software.
"We are recommending that staff should sign up to protecting software copyright as part of their contract terms and conditions," said Newton. "This gives employees no excuse for not knowing about activities that could lead to the prosecution of the company's directors."
Companies should treat infringement of copyright with at least the same severity as they treat explicit e-mails or the transmission of pornography, he added.
Newton denied that the BSA is being heavy handed. He said its main aim is to educate IT managers on how to avoid infringing copyright.
"Companies should apply the same diligence to managing software issues as they do to other assets," he said. "They should have an annual audit of the software on their computers or have audit tools which detect illegal software."