SAN JOSE, Calif. – A San Francisco Bay area subscriber to Comcast Corp.’s high-speed Internet service has sued the company, alleging it engages in unfair business practices by interfering with subscribers’ file sharing.

Subscriber Jon Hart based his claims on the results of an investigation by the Associated Press published last month that showed Philadelphia-based Comcast actively interferes with attempts by some high-speed Internet subscribers to share files online.

Hart’s lead lawyer, Mark N. Todzo of San Francisco, said his client suspected before reading the AP report that Comcast was interfering with his Internet traffic.

“What the AP report did was just confirm to him that it wasn’t just him who was suffering from the problem,” Todzo said. “There was this confluence of events where everyone seemed to reach the same conclusion, which was that Comcast was engaging in this activity.”

Other users claimed they had seen interference with some file-sharing applications. Subsequent tests by the Electronic Frontier Foundation confirmed the AP’s tests, which showed that Comcast is causing software on both ends of a file-sharing link to believe the connection has been dropped.

A coalition of consumer groups and legal scholars formally asked the Federal Communications Commission early this month to make Comcast stop interfering with file sharing. Two of the groups also asked the FCC to fine Comcast $195,000 for every affected subscriber.

Comcast is the country’s largest cable company and second-largest Internet service provider with 12.9 million Internet subscribers.

The company denies it blocks file sharing. But it acknowledged after the AP report was published that it delays some of the traffic between computers that share files.

Comcast said the delays are designed to improve the Internet experience for its subscribers as a whole. A relatively small number of file sharers is enough to slow down a network.

Hart’s lawsuit, filed Tuesday in Alameda County Superior Court, alleges Comcast misleads customers by promising “mind-blowing” speeds and “unfettered access” to the Internet in advertisements while hindering the use of certain applications such as peer-to-peer file sharing. It seeks unspecified money damages.

Todzo is seeking class action status for the lawsuit.

Comcast and its subsidiaries “intentionally and severely impede the use of certain Internet applications by their customers, slowing such applications to a mere crawl or stopping them altogether,” the lawsuit reads. “This class action seeks to end (Comcast’s) practice and seeks recovery of fees paid by customers who paid for services they did not receive.”

A Comcast spokesman reached late Wednesday said the company hadn’t been served with the lawsuit yet and could not comment.