Taiwanese cellphone maker HTC Corp. is filing a patent complaint against Apple Inc. over its popular gadgets, escalating a legal dispute as new smartphones are threatening the iPhone's supremacy.

HTC, which makes the Droid Incredible and other phones running competing Android software from Google Inc., filed a complaint with the U.S. International Trade Commission on Wednesday seeking to block U.S. sales of the iPhone, iPod and iPad devices.

Apple filed its own lawsuits against HTC in March, saying HTC's cellphones violate 20 of Apple's iPhone patents. Apple's complaints were made before the trade commission and in U.S. District Court in Wilmington, Del.

None of the complaints is likely to block sales of any products any time soon. Patent disputes are common among technology companies and often take years to resolve. The cases often lead to licensing agreements rather than outright bans on imports, as HTC is seeking in its complaint. Apple's products are typically made overseas.

The wild success of the first iPhone, launched in 2007, prompted other cellphone makers to rush out touch-screen smart phones of their own in a bid to lure consumers, not just business users attached to their BlackBerry phones.

At the end of 2009, iPhones made up about 14 per cent of smartphones sold worldwide, according to the research group Gartner Inc. Apple closed the gap with BlackBerry maker Research in Motion Ltd., which had 20 per cent of sales. But Android phones, while accounting for only 4 per cent of sales, grew at a faster rate than Apple last year.

HTC claims 5 patents violated

In the filing, HTC said Apple violates five patents.

In one, the technology helps prolong battery life by letting the phone system operate independently from the gadget's other functions. The phone might be in "sleep" mode while other programs are active.

In another, stored information is moved between different kinds of memory depending on how much juice is left in the battery.

The other three patents relate to how the phones store numbers, then looks them up and dial them.

Apple, which is based in Cupertino, Calif., had no comment on HTC's complaint, other than to point to its own legal actions against the cellphone maker.

Android phones, like the iPhone, support multitouch screens. Users sweep their fingers across the screens, and different "gestures" stand for different commands.

Among the patents singled out by Apple in its case against HTC is one that lets a device's screen detect more than one finger touch at a time — for instance, allowing someone to zoom in or out by spreading their fingers apart or pinching them together. Another patent refers to technology that helps a device react to information about its surroundings gathered by sensors.

HTC signed a patent-licensing agreement with Microsoft Corp. in April, presumably to avoid a legal tussle with another of the computer industry's biggest players.

Even if a legal decision is a long time coming, Apple's move against HTC could tamp down other mobile phone manufacturers' enthusiasm for Android if it seems hefty legal fees could erase the gains from using free software from Google.