Comcast Corp., the biggest U.S. cable-television service provider, was sued by a subscriber who claims the company violates antitrust laws by requiring customers to rent set-top boxes to access digital programs.

"The rental fees paid by each customer for the set-top box exceed its cost to Comcast or what the set-top box would sell for on the open market," attorneys for San Francisco resident Lucas Mays said in a lawsuit filed in federal court in Chicago.

The suit, filed Feb. 2, seeks class-action, or group, status on behalf of all Comcast digital-cable service subscribers. Mays asked for a court order barring Philadelphia-based Comcast from making rental of the boxes a requirement for subscribing to its digital service. Consumers can't buy the boxes separately from retailers, he claimed.

"Comcast does support third-party cable boxes," Sena Fitzmaurice, a spokeswoman for the company, said in a telephone interview. She declined to comment further on Mays's claims.

The case is Mays v. Comcast Corp., 09cv670, U.S. District Court, Northern District of Illinois (Chicago).