By Ian Youngs BBC News

Going to the library may not just mean pulling a book off a shelf

Many publishers put restrictions on how digital books and journals can be used.

Such digital rights management (DRM) controls may block some legitimate uses, the British Library has said.

And there are fears that restricted works may not be safe for future generations if people can no longer unlock them when technology evolves.

The British Library spends £2m of its £16m annual acquisitions budget on digital material, mainly reference books and journals.

This is going to be one of the significant challenges for us over the next few years Dr Clive Field British Library

But by 2020, 90% of newly published work will be available digitally - twice the amount that is printed - according to British Library predictions published last year.

Libraries are allowed to give access to, copy and distribute items through "fair dealing" and "library privilege" clauses in copyright law.

But as publishers attempt to stop the public illegally sharing books and articles, the DRM they employ may not cater for libraries' legal uses.

"We have genuinely tried to maintain that balance between the public interest and respecting rights holders," Dr Clive Field, the British Library's director of scholarships and collections told the BBC News website.

"We are genuinely concerned that technology inadvertently may be disturbing that balance, and that would be unhelpful ultimately to the national interest."

We have grave concerns about the potential use of DRMs by rightholders to override existing copyright exceptions Libraries and Archives Copyright Alliance

The All Party Parliamentary Internet Group is conducting an inquiry into DRM.

In written evidence, the Libraries and Archives Copyright Alliance (Laca) said there were "widespread concerns in the library, archive and information community" about the potentially harmful effects of DRMs.

"We have grave concerns about the potential use of DRMs by rightholders to override existing copyright exceptions," its statement said.

In the long term, the restrictions would not expire when a work went out of copyright, it said, and it may be impossible to trace the rights holders by that time.

"It is probable that no key would still exist to unlock the DRMs," Laca said. "For libraries this is serious.

'Threaten'

"As custodians of human memory, a number would keep digital works in perpetuity and may need to be able to transfer them to other formats in order to preserve them and make the content fully accessible and usable once out of copyright."

In its written submission to the group, the British Library said DRM must not "exert excessive control on access to information".

"This will fundamentally threaten the longstanding and accepted concepts of fair dealing and library privilege and undermine, or even prevent, legitimate public good access."

Fair dealing and library privilege must be "re-interpreted and sustained for the digital age", it added.