Apple has spoken out in the debate over whether users should be allowed to 'jail-break' mobile phones.

The controversial process involves removing hardware or software protections that limit the handset to a single carrier or software service.

Apple issued a filing in response to a campaign led by the Electronic Frontier Foundation (EFF) to create a new safe harbour under the Digital Millennium Copyright Act (DMCA) for mobile phone users.

The proposed exemption would allow users to remove software installation restrictions on their handsets. The procedure was popular in the early days of the iPhone, when users were not yet given an official option for installing and running third-party software on the device.

Apple has yet to pursue any legal action against users or developers for creating and running jail-breaking software, but has always discouraged the practice.

The company has long noted that the process will void the iPhone's warranty and that hacked phones could be damaged by subsequent software updates.

But Apple now appears to be taking a stronger stand by lodging an official complaint with the US Patent and Trademark Office.

"Apple is opposed to the proposed exemption because it will destroy the technological protection of Apple's key copyrighted computer programs in the iPhone device itself, and of copyrighted content owned by Apple that plays on the iPhone, resulting in copyright infringement, potential damage to the device and other potential harmful physical effects, adverse effects on the functioning of the device, and breach of contract," the company wrote in its official filing.

"The proponents of the exemption have also not satisfied their burden of proof of showing harm to non-infringing uses of the copyrighted works protected by the technological protection measures on the iPhone."

After receiving word of Apple's complaint, the EFF issued a statement of its own, blasting the company for what it called "absurd" arguments and "FUD" techniques.

"Apple casts its lot with the likes of laser printer makers and garage door opener companies who argue that the DMCA entitles them to block interoperability with anything that hasn't been approved in advance," wrote EFF senior attorney Fred von Lohmann.

"But we'd never accept this corporate paternalism as a justification for welding every car hood shut and imposing legal liability on car buffs tinkering in their garages."