NEW YORK - Comcast, the nation’s largest cable company, has sent a cease-and-desist letter to the NFL Network demanding the channel’s representatives stop encouraging fans to leave the cable provider.

Dallas Cowboys owner Jerry Jones, the outspoken chairman of the league’s NFL Network committee, has urged customers of Comcast and other large cable providers who don’t carry the network on a basic tier to switch to satellite or other cable services that do.

The channel’s iwantnflnetwork.com Web site includes a box titled “MAKE THE SWITCH.” Above a field to enter a zip code, the text reads, “Switch to a TV provider that will bring you NFL Network, not hold you hostage.”

The letter, dated Monday, contends that such actions violate the contract between the network and Comcast.

“The legal arguments are without merit, and Comcast subscribers who are dropping that service do not need encouragement from us,” said NFL Network spokesman Seth Palansky, who added that network executives had not yet received the letter.

The two sides have gone to court over their agreement. The NFL Network sued Comcast after the cable provider decided to move the channel from its basic digital tier to a premium sports tier that customers must pay extra to receive.

In May, Manhattan state Supreme Court Justice Bernard J. Fried ruled in favor of Comcast. The network has appealed.

The letter requests that the network confirm in writing by the close of business Friday that it has halted its efforts to influence customers. Comcast spokeswoman Jennifer Khoury said she didn’t want to speculate what the company would do if its demands were not met.

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The network, launched in 2003 to provide 24-hour coverage of the league, began airing live games late last season. This year’s eight-game package kicks off Thursday night with a matchup between the Indianapolis Colts and Atlanta Falcons.

The network is available in about 35 million of the nation’s more than 111 homes with televisions, which Jones conceded is far fewer than he hoped it would reach by this point.

The NFL Network’s initial strategy was to encourage fans to ask their cable companies to add the channel. Jones acknowledged earlier this month that the focus had shifted. He said cable executives “dared” him to prove that viewers so desired the network that they would switch providers.