PHILADELPHIA, Pa. – Comcast, going after consumers willing to pay top dollar for the fastest Internet speeds, introduced a $299.95-a-month service on Tuesday that it says beats the speediest offering from Verizon Communications Inc. (VZ)’s FiOS.

The new tier, called Xfinity Platinum Internet, offers download speeds of up to 305 megabits per second, Comcast said in a statement. The Verizon FiOS business, which relies on fiber-optic lines, introduced a plan in June that tops out at 300 megabits for $204.99 a month with a two-year contract.

They are offering the highest speed Web access, called Xfinity Platinum Internet, with download speeds of up to 305 megabits per second.

By offering services that let consumers download movies in a few minutes and photos and songs in seconds, the companies are jockeying for bragging rights as the fastest provider of residential Internet service in the U.S.

The idea is to target “really advanced digital families,” said Charlie Douglas, a spokesman for Philadelphia-based Comcast. The speed also helps when households have lots of digital devices sharing the same Internet connection.

Internet traffic is expected to increase fourfold by 2016, according to an annual survey by Cisco Systems Inc.

For now, though, most home Internet users might not notice a difference in speed beyond 25 to 50 megabits, according to Jonathan Atkin, an analyst with RBC Capital Markets in New York. And other broadband providers haven’t yet joined the speed race: Time Warner Cable Inc. (TWC), the second-biggest cable company, offers a top rate of 50 megabits for $99.95.

Comcast is introducing the new speed tier in its hometown and other Northeastern cities, including Boston, Pittsburgh, Baltimore and Washington. The service includes around-the-clock technical support, with a dedicated consultant to answer questions, a wireless gateway for connecting to Wi-Fi devices, and a suite of online security services.