BT has become the latest in a line of tech companies to take on internet giant Google in the courts over a number of alleged patent infringements.
BT's case focuses on six patents, which relate to technology used in Google's Android mobile system, its search site and its Google Maps service.
The telecoms giant has filed legal proceedings at the US District Court of Delaware and is seeking unspecified damages as well as an injunction against Google's continued use of its innovations.
The move follows legal action by Apple, Microsoft, Oracle and others, which have all made claims against Google's Android system.
A BT spokesman said: "This is about protecting BT's investment in its intellectual property rights and innovation. It is a well-considered claim and we believe there is a strong case of infringement."
A Google spokeswoman said: "We believe these claims are groundless and we will vigorously defend ourselves against them."
If successful, the suit could mean that Google or mobile handset makers will have to pay BT royalties on each Android handset in use and which they produce.
In documents submitted to the courts, BT claims Google offers a range of products and services that "incorporate" technology invented by BT prior to Google's founding.
BT claims services including Google Music, Android, Google Plus, Google Maps, Google Books and eBooks all infringe BT's own patents.
BT has a total worldwide portfolio of around 5,600 patents and applications.
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