Apple has amended its complaint against Qualcomm in the US to allege the company double-dipped and unfairly received billions of dollars. The complaint was filed with a US federal court in San Diego. Apple says Qualcomm's unfair licensing practices have led to unnecessary expenditures beyond a billion dollars.

This expands upon the original case, which involved Apple demanding $1 billion from Qualcomm to cover unpaid royalty rebates.

Even though Qualcomm is only a supplier for a small part of the iPhone, it calculates its royalties based on a percentage of the iPhone's sale price. Apple says this is unfair and has led to significant overpayments.

Apple wants the legal system to find Qualcomm's patents aren't essential to the iPhone's 3G/4G standards.