The U.S. International Trade Commission has accord to enquire Apple based on a complaint filed by handset maker HTC , the Commission articulate on Friday .

The agency is already enquire HTC after Apple filed its own complaint against the company . The contravention highlights how competitive the smartphone market has become .

HTC make smartphones based on Google ’s Android package , as well as Windows Mobile devices . In May it asked the ITC to block the importation of iPhone , iPad and iPod products to the U.S. , turn on Apple with infringing five of its patent .

It has n’t stated publicly which patents it believes Apple infringed , but the ITC offer some hint . “ The products at issue in this investigation are portable electronic devices that utilize certain power management methods and may incorporate computer hardware and software for telephony directory within mobile telephony systems , ” the authority said .

An administrative constabulary justice for the ITC will apply an evidential audience to wait into HTC ’s ill . The agency has 45 days to do a objective date for completing the investigation .

The ITC has already agreed to investigate HTC base on a exchangeable complaint filed earlier by Apple . Apple says that HTC uses patent related to the iPhone ’s user port and a range of hardware and package technology .

As the market for smartphones heat up up , the primary players are becoming increasingly contentious . Apple is also in a dispute with Nokia over patents . Research In Motion and Motorola settled a patent lawsuit on Friday .

Separately , HTC agree to pay royalties to Microsoft for technology used in all of its phones race Android . Google , which designed Android and has an increasingly bitter relationship with Apple , has largely remain out of the fight . After Apple charge its complaint against HTC , Google said it stand by the operating system of rules and the spouse that helped develop it .