BT (London), Britain's dominant fixed-line telecoms group, said in a statement on Monday that it had filed a claim with the U.S. District Court of Delaware for patent infringement.
The BT claim relates to six patents which BT says are infringed by such services as Google's (Mountain View, Calif., U.S.A.) highly successful mobile platform Android , Google Maps, Google Music, advertising services, gmail and other products.
"This is about protecting BT's investment in its intellectual property rights and innovation," the group said. "It is a well-considered claim and we believe there is a strong case of infringement."
A widespread patent battle has broken out within the telecoms industry as increasing numbers of operators, handset makers and content providers seek to offer attractive services such as maps and entertainment to consumers.
Google is already facing a number of patent disputes  with companies such as Apple (Cupertino, Calif., U.S.A.), Microsoft (Redmond, Wash., U.S.A.) and Oracle (Santa Clara, Calif., U.S.A.), while manufacturers of Android-based phones such as HTC are also facing claims.
A Google spokesman said the group believed the claims were groundless. "We will vigorously defend ourselves against them," he said.
BT says it has a total worldwide portfolio of around 5,600 patents and applications, filing for patent protection on 62 inventions during the last financial year alone.
Florian Mueller, an IP analyst who has closely followed the twists and turns of patent litigation, said on his website that BT had become the fifth large publicly traded company to bring patent infringement litigation against Android.
"With so many major patent holders asserting their rights, obligations to pay royalties may force Google to change its Android licensing model and pass royalties on to device makers," he said.
"Android already had more than enough intellectual problems anyway. Now Google faces one more large organization that believes its rights are infringed. BT probably wants to continue to be able to do business with all mobile device makers and therefore decided to sue Google itself."
In August, Google agreed to buy Motorola Mobility for $12.5 billion , its biggest acquisition ever, in part as insurance against increasingly aggressive legal attacks.
Motorola has one of the mobile industry's largest patent libraries.