Apple has won a preliminary ruling from a US trade panel judge that Taiwanese handset maker HTC Corp infringed on two of the California company's patents.

The win may mean Apple can go after other Android handset makers for licence fees, though the decision must still be ratified by a full panel. It could also allow Apple to demand an import ban to the US against HTC before the end of the year.

HTC, which uses Google's Android operating system for its smartphones, said it would "vigorously fight" the infringement finding.

The risk for Android handset makers is that it is very likely that all Android devices infringe the patents, which were filed in 1994 and 1996, says Florian Mueller, an expert on the many patent battles swirling around the smartphone business.

Apple has also filed complaints against Samsung and may be able to attack Motorola on the same basis.

The relevant patents cover "system and method for performing an action on a structure in computer-generated data", US patent No. 5,946,647, filed in 1996 and awarded in 1999.

Essentially, it allows elements such as email addresses or phone numbers to be recognised so that when they are activated via a mouse or, on a smartphone, by a finger, they activate the relevant program.

Apple implemented this idea as "Data Detectors", implemented by Apple's Advanced Technology Group – which Steve Jobs disbanded when he took over as chief executive in 1997.

Apple pointed out the infringement in detail, noting that Android contains an "analyser server" for "detecting structures in the data" and further details that exactly align with the outline of its patent.

The second patent, "real-time signal processing for serially transmitted data", of US Patent No. 6,343,263.

The patent was applied for in 1994 and will expire in 2019, and Apple provides a detailed breakdown on why it infringes in court documents filed with the ITC.

The ruling came from an International Trade Commission judge on Friday, but the full commission must rule on 6 December whether it will uphold or reverse it.

Though preliminary, the ruling will be closely dissected as it is one of the first between Apple and other smartphone makers that use Android.

HTC is already believed to be paying Microsoft $5 per handset for licensing rights after acceding to claims that its handsets' implementation of Android infringed a number of Microsoft patents.

Microsoft has also demanded – and received – payments from at least three other companies building products around Android in the past month.

Asked for comment by Reuters, Apple reiterated a previous statement by Jobs that "competitors should create their own original technology, not steal ours." In an emailed statement, HTC lawyerGrace Lei said: "We are confident we have a strong case for the ITC appeals process and are fully prepared to defend ourselves using all means possible."

Smartphone technology has spawned a wealth of patent litigation. Apple also has filed complaints against Samsung Electronics, which also uses the Android software platform. Apple recently settled a case against Nokia.

Android-based smartphones have outpaced iPhones globally but Apple is gearing up to launch a new iPhone this year, which is likely to give it a big boost.

Apple initially accused HTC of infringing 10 patents, but six were dropped from the case for various reasons. The ITC judge ruled that HTC infringed two of the remaining four.

The ITC is a popular venue for patent disputes because it can bar the importation of devices made with infringing technology. Often parallel lawsuits are filed in district courts to try to recoup any financial damages.

The case is at the International Trade Commission, No. 337-710.