LONDON — The technology industry is expanding its fight against patent trolls to Europe.

In the United States, technology companies like Google, Apple and Microsoft have spent years and hundreds of millions of dollars to defend patent-infringement lawsuits by companies that make a business of buying technology patents primarily for suing software companies and makers of products like smartphones. Now they worry that Europe could soon become a broad battleground for similar court battles.

In a letter to be sent to European officials on Thursday, 14 companies outline their concerns about a coming change that will give most of Europe a unified patent court system for the first time. So far, the technology industry has generally supported this pan-European effort as a better way to protect intellectual property, compared with the current thicket of country-by-country rules.

But in looking at the details of the new approach, tentatively scheduled to begin in 2015, the companies now fear that the new system could be vulnerable to what they call patent assertion entities, less politely known as patent trolls, which make a business of filing patent-infringement suits. Such companies say they play a valuable role in protecting innovators, but many corporations see the suits as frivolous and damaging. In the United States, the Federal Trade Commission has a patent-troll investigation under way.

In interviews, executives of some of the companies that sent the letter said one of their concerns was that court-shopping by patent trolls in some smaller European countries could turn parts of the Continent into the equivalent of the Eastern District of Texas. That federal court jurisdiction has become an American capital of patent litigation known for sympathetic juries and speedily moving cases.