Comcast Corp., the largest U.S. cable provider, will double the speed of its Internet service for current subscribers and offer even faster connections at additional cost to improve movie, music and game downloads.

In the next few weeks, the so-called DOCSIS 3.0 services will be available to subscribers in parts of New England, Philadelphia and New Jersey, the Philadelphia-based company said in an e-mailed statement today. The service will expand to more than 10 million homes and businesses by the end of the year.