PHILADELPHIA — Without a last-minute agreement, the NFL Network might be unavailable on Comcast Corp.'s cable TV systems beginning Friday.

Comcast and the National Football League are in a court battle over Comcast's decision to put the NFL-owned channel in a premium sports tier rather than in a lesser-priced service package that has more viewers.

The agreement under which Comcast carries the NFL Network was due to expire at 11:59 p.m. Thursday. Comcast said it would be willing to carry the channel under the same terms while the litigation goes on, but the NFL hasn't accepted the offer. NFL Network spokesman Dennis Johnson said the network is willing to talk. But without an agreement or extension, Comcast expected to pull the plug at midnight.

Comcast, the nation's largest cable company, said the NFL asked for a 350 percent increase in the fees it would pay to carry the network, according to documents filed with the Federal Communications Commission.

Since the fees are based on the number of viewers, Comcast was able to pay less to the NFL Network by moving the channel from a digital tier with 8.6 million subscribers to a sports package that has 2 million subscribers and costs an extra $7 per month. The Philadelphia-based cable operator said it was allowed to do so under their contract, signed in 2004.

The NFL said Comcast made the move in retaliation for not getting the rights to show eight live NFL games for its Versus sports channel.

The NFL pointed out that Comcast rivals such as Dish Network Corp., DirecTV Group Inc., Verizon Communications Inc. and AT&T Inc. all agreed to the same rates to carry the network. The NFL Network also said that with a smaller audience, it couldn't get sports packages like Pac-10 Conference college football games, which had a minimum viewership requirement.

In 2006, the NFL sued Comcast in New York state court to force the cable operator to move the network back to the more popular digital tier. The following May, the court sided with Comcast.

The NFL appealed. An appellate court partially reversed the state court ruling and sent the case back for discovery and trial, where it is pending today.

In the meantime, the NFL sought an FCC order on the dispute. Now the case awaits a ruling from an administrative law judge at the FCC.