Las Vegas ? Some of Las Vegas’ biggest hotel-casinos are canceling Super Bowl parties and making refunds to thousands of guests after the NFL threatened legal action against those broadcasting the title game on big-screen TVs.

Several hotels received letters last week informing them their parties were “unauthorized use of NFL intellectual property.”

NFL spokesman Brian McCarthy said the league only recently became aware of large parties planned in Las Vegas and elsewhere around the country.

“These establishments were attempting to charge admission for something we are offering for free, and we believe that’s a violation of a long-standing NFL policy that specifically prohibits mass out-of-home broadcasts,” McCarthy said.

In determining whether an event violated the NFL’s copyrights, the league considered the location’s size, whether TV screens were larger than 55 inches and whether people had to pay to get in.

Some hotels have scrapped party plans entirely, while others are scrambling to accommodate the estimated 274,000 visitors expected to come to Las Vegas for Super Bowl weekend.

“As far as I’m concerned, the NFL is full of soup,” Mayor Oscar Goodman said. “I would tell them to go shove it.”

A Super Bowl party inside a movie theater at the Palms was scrapped after the hotel received a letter from the league Jan. 23. The gathering usually attracts several hundred people, who enjoy hot dogs and beer and compete in games and raffle drawings for $39.99.

The off-Strip hotel decided to rent dozens of smaller TVs that will be set up in a hotel ballroom, and the beer and hot dogs will be free, said general manager Jim Hughes.

“The Palms is all about the party, and we want to make sure anyone who comes to the property is still going to have a good time,” he said.

The Aladdin hotel-casino had to cancel its bash at the hotel’s 7,000-seat Theatre of Performing Arts after receiving an NFL letter Friday. Officials scrambled to find small TVs that they could place throughout the casino for guests wanting to watch the Super Bowl.

“The city has had events like this for years,” said Tyri Squyres, an Aladdin spokeswoman.

Casinos’ sports books were not affected. Last year, about $73 million was wagered on the game, according to state gambling officials.

Goodman said Las Vegas was being unfairly targeted, charging the league had allowed “a condition to exist for the past 10 years, and then they want to change the rules two days before.”

McCarthy dismissed claims that Las Vegas was being singled out, saying the NFL had sent letters to several locations in Boston; Charlotte, N.C.; and Houston.

“When we become aware of a potential violation, we take action,” McCarthy said. “It’s not a city issue, it’s a copyright issue.”

The NFL’s letter was particularly devastating to promoter Todd Krohn, who had organized a party at The Orleans hotel-casino that was expected to draw about 6,000 sports fans at $45 a ticket. He estimated the cancellation cost his company, T & J Trust, more than $100,000.

“Our biggest problem with this was the late notification. If the NFL had made this decision, why didn’t they give us 30 days notice?” Krohn said. “We wouldn’t have scheduled the event. We wouldn’t have spent the money.”

Professional gambler Tom Burton said the hotels were providing a community service by televising the game.

“You can’t go to the Super Bowl because all the seats are taken,” he said. “The NFL just wants to dig deeper and deeper and wants to get as much money as they can. When is it going to end?”