Apple is cracking down on websites that sell access to pre-release, beta versions of its iOS6 iPhone and iPad software.
Beta software is incomplete, and Apple only makes it available to software developers for testing purposes.
The websites charge about $10 (£6.45) to register an individual device so that it can run iOS6 beta software.
Apple has sent legal notices to web hosting companies requesting that they disable the websites.
Apple offers the latest finished versions of its iOS mobile operating system free, but charges registered developers $99 (£63.85) to access beta versions.
This payment entitles developers to "activate" the Unique Device IDentifier (UDID) numbers of up to one hundred iOS devices with Apple so that they can run iOS 6 beta software. iOS6 is expected to be released later this year.
Activation websites register developer accounts and pay Apple for a hundred device activations, and then sell these off individually at a profit.
"We have paid the fees and done all the work. All you have to do is register your iOS device on our account. Once you register, you'll be able to download the beta firmware and install it on your device," promises one activation site.
Within the last month Apple has issued DCMA (Digital Millennium Copyright Act) takedown notices to Fused, a Seattle-based web hosting company, in relation to activation websites it hosts, according to Fused chief executive David McKendrick.
A DCMA takedown notice is a formal way for a copyright holder or their agent to demand removal of allegedly infringing content from the Internet.
The sites in question had been active for three months, Mr McKendrick said, and Apple claimed in the notices that they breached its developer agreement or facilitated copyright infringement.
"This is definitely a new move on Apple's part," he said.
Apple prohibits developers from providing pre-release software to anyone other than their employees and contractors who have a "demonstrable" need to use it to develop and test applications on their behalf.
But Mr McKendrick added that Apple's action was unlikely to be effective, because many of the sites in question were in the process of moving their sites to hosting firms based outside the US.
"Apple is definitely fighting a losing battle on this one. Unless they go directly after the developer accounts abusing the process, they have little chance scrubbing these sites off the web," he said.
Apple declined to comment.
Activation websites exploit the willingness of some Apple device owners to pay to get access to the very latest versions of iOS6 before they are officially made available - despite the fact that beta software is often prone to crashing and may not include all the features that appear in the software when it is finally released.
The websites may also appeal to developers who are unwilling to pay the full $99 to become a registered developer.
Google does not charge developers to run its Android mobile phone or tablet software.
Last week the European Union published a judgement stating that software vendors cannot prevent customers from selling the licences to software they no longer wish to use, even if the licence agreement prohibits it.
Aaron Wood, head of trademarks and brand protection at IT law firm Briffa, said that if a single developer or a company paid a fee to register up to 100 devices then while they may be allowed to sell this entitlement on as a job lot to another person or organisation, splitting the entitlements and selling them to different users would probably not be legal.
"Apple certainly doesn't want you to buy a hundred licences at a preferential rate and then sell them off piecemeal," he said.
But the EU judgement will have significant implications for software makers who attempt to restrict the second-hand market for their software, according to Mr Wood.
"If I buy software for home use then I shouldn't be restricted from selling it on for home use," Mr Wood said.
But he warned that buying home or student software licences and then selling them to businesses would not be allowed. "You can't sell software licences with a right you never had," said Mr Wood.
One implication of the EU judgement is that software vendors will have to provide some way for customers to free up licence keys when they uninstall software so that they can be reused by subsequent purchasers, he added.