Two California residents have sued Comcast Corp. over its plan to create a national WiFi network through Xfinity wireless routers, claiming it would drive up electric costs for subscribers, slow Internet speeds, and pose security risks.

The suit, filed in federal court in Northern California, seeks class-action status and says Comcast wants to compete with wireless companies with its WiFi network, which relies heavily on routers in Xfinity subscribers' homes.

Comcast said Friday that it disagrees with the allegations in the suit and asserts that the WiFi home hot-spot program "provides real benefits to our customers" because of the low cost of WiFi downloads compared with cellular downloads.

Comcast also said it gives its Xfinity customers information on how to disable the function that allows public access to the WiFi router.

Xfinity home hot-spot routers operate with two channels: a private one for the subscriber's use, and a public one for access by other Xfinity subscribers within WiFi range.

Comcast has said it expects to activate eight million WiFi hot spots by January, many based on these home routers. Routers in the Philadelphia area are part of the program.

"Without authorization to do so, Comcast uses the wireless routers it supplies to its customers to generate additional, public WiFi networks for its own benefit," according to the suit, filed Dec. 4 by Joycelyn Harris and Toyer Grear of Alameda County via the law firm of Milstein Adelman L.L.P.

The suit cites a study by Philadelphia technology company Speedify that estimates that Comcast could eventually push tens of millions of dollars in electric costs for its WiFi network onto Xfinity subscribers.

Public access through the home routers also consumes valuable WiFi bandwidth in a subscriber's home - potentially slowing Internet speeds, the suit claims.

Because the routers allow strangers onto the "the same wireless router used by Comcast customers in their homes, the data and information on a Comcast customer's network is at greater risk," according to the suit.

Comcast said on Friday it expects "minimal impact" to Internet speeds and it uses the same security standards as online banking services with the routers, protecting Xfinity subscribers.