Taiwanese smartphone giant HTC has launched legal action against Apple in the UK courts.
Details of the suit are not available until Apple has acknowledged the complaint and neither company has made any statement about the fresh action.
The move is the first European battle since the start of the ongoing US patent battle between the two companies.
HTC and Apple have both secured ITC wins against each other which raises the prospect of an import ban into the US market unless a deal can be reached. However HTC's win against Apple using a freshly-acquired S3 graphics patent only applies to the Mac, not the iPhone.
Intellectual property activist Florian Mueller pointed out that Apple had further patent disputes yet to reach the courts and is of the belief that Apple's victory over HTC is assured.
"The question is only how quickly Apple will prevail. Not if," said Mueller.
Mueller also took issue with analysts claiming that the worst case scenario for HTC and other Android smartphone makers was that a licensee fee of around $5 would be payable to Apple for every handset.
He believes Apple will not license the patents at any cost in order to force rivals to either exit the market or substantially redesign their products.
"The only way HTC can get a patent license from Apple is if they bring patents to the table that Apple needs, and in that case I could see a (partial) cross-license happen, with or without some additional payment."