HTC was the first manufacturer to use Android in its phones
Apple's legal action against HTC may have "wider implications" for all phone makers using Google's Android operating system, an analyst has warned.
Ian Fogg of Forrester Research said that the case against HTC, in which Apple alleges infringement of 20 of its patents, could be the first of many.
Although Apple has not named Google in the suits, many of the named patents relate to operating system processes.
Google has taken the unusual step of publicly supporting HTC in the case.
"We are not a party to this lawsuit," said a Google spokesperson.
"However, we stand behind our Android operating system and the partners who have helped us to develop it."
HTC was the first manufacturer to use Android in its phones and is also the maker of Google's own brand Nexus One handset.
Some have speculated that Apple - which makes the popular iPhone - are attacking Google "by proxy" by filing the case against HTC.
"I think this is kind of an indirect lawsuit against Google," analyst Shaw Wu of Kaufman Brothers told Reuters.
Some of the patents that Apple alleges have been infringed are 15 years old and cover aspects of operating systems.
As a result, some believe that the patents cannot just relate to HTC and believe the case may just be an opening salvo against other firms and possibly Google.
"Simply because Apple has focused on HTC now doesn't mean it won't take action against other manufacturers later," Mr Fogg told BBC News.
Apple is in the middle of several patent disputes
"[This case] could have implications for all other phone manufacturers which have just announced their phones at Mobile World Congress."
Mobile World Congress is a showcase for the phone industry, held every February in Barcelona, Spain.
Manufacturers including Sony Ericsson, LG, Samsung and HTC announced new handsets running Android at the show.
"2010 is going to be the year of Android," said Mr Fogg.
Apple announced the legal action against HTC on 2 March.
In a statement Apple boss Steve Jobs said: "We can sit by and watch competitors steal our patented inventions, or we can do something about it.
"We've decided to do something about it."
The Californian firm alleges that HTC have infringed 20 patents owned by Apple that are used in the iPhone.
Apple is seeking an injunction which would effectively bar HTC from selling phones that use the disputed technology in the US.
The legal action has been filed with the US International Trade Commission (ITC) and a district court in Delaware.
HTC has said it is unable to comment on the case until it has had a chance to assess the validity of the claims.
It is the latest in a series of legal wrangles involving Apple.
Finnish phone giant Nokia sued Apple for patent infringement in October 2009, alleging it had stolen patented technology.
In response, Apple countersued in December 2009, followed by a second round of legal action from Nokia.
Apple is also being investigated by the ITC following a complaint by camera manufacturer Kodak. The firm alleges that the iPhone uses technology for previewing pictures that infringe Kodak patents.