Negotiators from 186 countries are in Marrakech this week trying to hammer out the text of an international treaty that aims to make copyrighted works more readily available to the world's blind and visually impaired people, 90% of whom live in the global south.

Observers say the treaty, which has been in the works at the World Intellectual Property Organisation since 2008, is likely to be finalised before the end of this week. But the scope of the treaty, which seeks to lift copyright restrictions on published works in the interest of blind people, has come under intense pressure from one of the most powerful lobbies in the US: Hollywood.

"The Obama administration has an extremely intimate relationship with the motion picture industry with regard to these negotiations," said James Love, director of Knowledge Ecology International, a non-profit organisation with offices in Washington and Geneva.

Love was the force behind a recent freedom of information request that revealed extensive communication (pdf) between the film industry and the US Patent and Trademark Office (PTO), which has been leading the US delegation in the treaty talks.

The request revealed "142 pages of emails [over] just a couple of months' period, and that was just with one agency of the government", Love said. The film industry is "trying to micro-manage the US government's position on a treaty involving blind people", he added.

Representatives of the industry hired lawyers to offer advice on the treaty language, which was passed on to the PTO, as evidenced in the emails. In one message from February, Justin Hughes, the lead US negotiator, asked whether one of those hired lawyers might "have any views on [a controversial subject] that you might solicit and we might use to counter [other countries' positions]?"

Copyrighted audiovisual works – such as films and slideshow presentations – are not even going to be covered by the treaty, which is limited to print works. But that has not always been the case.

In June 2011, several countries – including the US and EU members – jointly put forward a proposal (pdf) suggesting that a treaty for visually impaired people should cover all copyrighted works "in any media".

But by July 2012 (pdf), negotiators had started wrangling over the definition of the "works" to be covered by the treaty. The phrase "in any media" had been put into square brackets, indicating that it was a source of disagreement among the parties, while a phrase limiting the works covered to "text, notation and/or related illustrations" had been introduced, also in brackets. Audiovisuals have been off the table ever since.

In effect, Love said, the impact of this shift, which he says was led by the US, is enormous. "If there's a training video or an educational video, you can't touch the content of that in order to make it accessible to a blind person," he said.

Among the groups shown to be in active communication with the US government are Paramount Pictures, Time Warner, Warner Brothers and – most of all – the Motion Picture Association (MPA), which represents Hollywood interests.

Chris Marcich, director of the MPA's operations in Europe, the Middle East and Africa, insists his organisation does not have an unduly close relationship with the US officials. "The US government tries to balance the positions of various stakeholders, and we're one of them," said Marcich, who spent more than a decade working in the Office of the US Trade Representative in the 1980s and 1990s.

He insisted that his organisation is simply interested in ensuring the treaty contains appropriate "checks and balances". If the copyright exceptions are too loose, he said, they "could be used by someone who's interested in something other than serving the interests of a visually impaired person … Maybe a commercial entity wants to try to make money off of an exception."

But many developing country delegates worry that the copyright exceptions that end up in the final treaty may be so complex as to make them virtually useless to blind and visually impaired people in the global south.

Ruth Okediji, an intellectual property professor who is representing Nigeria in the negotiations, stressed the importance of including usable copyright exceptions in the text of the treaty.

"Even though there are rules in the copyright system that help strike a balance between rights holders and the public, those rules are not sufficient to address the needs of the blind," said Okediji, who admitted she was "surprised" and "disappointed" to discover the extent to which the film industry was lobbying for a weaker treaty.

"No country should be comfortable in a world where the blind or visually impaired have less access to works than sighted persons," she added.