* IPCom says has sued German retailers
* IPCom won injunction against HTC almost 3 years ago
* Ruling became enforceable after HTC pulled appeal in Nov (Adds details)
FRANKFURT, Dec 22 (Reuters) - Patent firm IPCom has sued German retailers for patent infringement for continuing to sell phones made by HTC, the No. 4 smartphone vendor globally.
A court in Mannheim, Germany, ruled in February 2009 against HTC in a patent fight with IPCom, allowing an injunction against sales of HTC phones using UMTS technology and setting a penalty of up to 250,000 euros ($326,200) each time the injunction was contravened.
All HTC smartphones use UMTS technology.
In late November, a court in Karlsruhe, Germany, said the injunction against HTC smartphone sales in Germany could be enforced after HTC dropped an appeal.
IPCom said in a statement on Thursday that it sent 100 retailers cease and desist requests on Dec. 6, asking them to stop selling HTC's 3G handsets by Dec. 20.
"Since this deadline has passed without any of the retailers complying, IPCom has sued them for infringement of patent #100A themselves," IPCom said, adding so far it has sued around 30 retailers.
The legal battle could cost HTC millions of euros and hurt its relations with retailers in one of its key markets.
The company sells around 2 million smartphones a year in Germany, some 4-5 percent of the group's total, according to research firm IDC.
"This poses another challenge for HTC in managing confidence of key distribution partners -- a further reminder of the destabalisation effect patent claims threaten to exert on the industry in 2012," said Geoff Blaber, analyst at research firm CCS Insight.
HTC was not immediately available to comment.
It has said the battle would have no impact on its business in Germany because the injunction covered only one HTC handset - which is no longer sold in Germany - and it has also modified its implementation of the UMTS standards.
The ruling does not mention any particular model.
Earlier this week HTC lost a patent case against Apple in the United States, the market generating half of its revenues, but HTC said that it could soon replace phones with the disputed technology with new models.
IPCom acquired Bosch's mobile telephony patent portfolio, created between the mid-1980s and 2000, which includes about 160 patent families worldwide, including some of the key patents in the wireless industry, such as patent 100, which standardises a cellphone's first connection to a network.
Several of the top phone makers have signed a licensing deal with it, but HTC and Nokia have challenged IPCom's technology patents in courts across Europe.
IPCom said by continuing to use its patents without paying a fair compensation IPCom could in the future legally refuse HTC a licence for its standard-essential patents. ($1 = 0.7664 euros) (Reporting by Christoph Steitz and Tarmo Virki; Editing by David Cowell)