Internet at public libraries could be on the chopping block as a result of new anti-piracy laws, says the library association.

The association, LIANZA, says libraries do not record the internet activity on their computers so it is impossible to track down and stop anyone downloading movies or music.

Parliament passed changes to the Copyright Act last month allowing copyright holders to issue warnings to those believed to have illegally downloaded content. A third suspected infringement allows the rights owner to seek a court order to fine offenders $15,000.

Under the law, which takes effect in September, libraries would end up paying the fine because the account owner was responsible for any illegal downloading, said LIANZA's Tony Millett.

"The legislation appears to assume that, first of all, the account holder is a single person and the only person using the machine, which of course in a library is not what happens. The whole thing is an absolute nightmare and we really don't see how it is going to work."

If libraries were being hit with $15,000 fines, councils would demand they do something to stop illegal file-sharing, Mr Millett said.

"One solution is withdrawing access to the internet altogether."

He said the internet was a key attraction of libraries and in hot demand from both locals and tourists.

"If you go to any library, anywhere in the country, you will find machines are always in use ... People use it for email, they use it look up things."

Libraries had a responsibility to try to stop illegal downloading but cutting off access was "draconian" and should be a last resort.

He said these concerns were raised at a select committee hearing but MPs did nothing to address the problem.