A Palmerston North librarian says rumoured copyright changes would be a "tragedy" for the city library.

Current New Zealand copyright law releases content for public use 50 years after the death of the author.

The United States entertainment industry is pushing to extend the term of copyright, possibly to 70 years after death, as part of the Trans-Pacific Partnership Agreement (TPPA).

The TPPA is a commercial trade agreement being negotiated among 11 Pacific-bordering nations including New Zealand, the US and Australia.

Palmerston North Digital Services librarian Warrick Taylor said any extension of copyright would have a big impact on the library's digital content.

The library had spent $16,000 last year digitising issues of the Manawatu Standard between 1904 and 1910 and the Manawatu Times up to 1908, but these would likely have to be pulled, Mr Taylor said.

Some of the digital content on Pataka Ipurangi (digital library), which was used for general research and family histories, would also have to be taken down.

"It would be a tragedy for our programme.

"In an internet age, we don't need stronger copyright, we need smarter copyright."

He was concerned the desire for copyright change was not coming from Australian or New Zealand companies, but from American companies.

"It's a frustration because the copyright extension doesn't seem to do anyone any favours other than Mickey Mouse."

Copyright should be a balance between creators and users, but any changes would only favour creators, he said.

"Ninety-nine per cent of what will be copyrighted [if laws change] should be made available.

"I really don't see an up-side . . . With modern digital services, if anything we should be reducing copyright to 30 or 40 years after death."

Feilding Public Library manager Simon Johnson said the potential for copyright change was another example of how digitising and copyright was becoming a "digital Wild West".

The change would not influence Feilding too much as its digital content was not as extensive as at larger libraries.

But Feilding would extend its content in future and at that time it would definitely be affected by copyright changes, he said.

"It's going to hamstring the ability of all libraries to provide the public with information.

"I'd be very concerned with what is driving this."

Trade Minister Tim Groser, who is a part of TPPA negotiations, was unavailable for comment.