LAS VEGAS (AP) – A federal prosecutor has snuffed out plans by pot fans to celebrate Nevada’s new recreational marijuana law by lighting up on an American Indian reservation near Las Vegas.

U.S. Attorney Daniel Bogden took a hard line in a letter to organizers of a weekend cannabis festival, saying federal law applies and pot smokers could be prosecuted.

Bogden wouldn’t comment Friday beyond referring to the Feb. 16 letter he sent to the Moapa Band of Paiutes.

The warning from the top federal prosecutor in Nevada came while several U.S. senators are airing concerns about the possibility of a Trump administration crackdown on marijuana use in states that have legalized pot for recreational or medicinal purposes.

Sen. Catherine Cortez Masto of Nevada joined nine other Democrats and one Republican, Alaska Sen. Lisa Murkowski, in signing a Thursday letter to U.S. Attorney General Jeff Sessions.

U.S. Sen. Dean Heller, R-Nev., sent a similar letter to Sessions on Wednesday.

Organizers of the High Times Cannabis Cup festival said there will still be music, T-shirts and souvenirs at the event at a Moapa Band of Paiutes festival site.

But spokesman Joe Brezny said it will essentially be just a concert this year.

“We’ve removed the marijuana,” he said. “There will be no smoking area, no edibles competition, no cannabis topicals or lotions.”

Brezny said more than 10,000 tickets were sold this week for the two-day event Saturday and Sunday at a site about 35 miles north of the Las Vegas Strip. The concert is headlined by hip-hop artist Ludacris.

Robert Capecchi, federal policies chief at the Marijuana Policy Project advocacy group in Washington, D.C., said a lot of attendees might be disappointed or upset that they can’t smoke on site.

But he noted that laws are different in federal areas within the eight states that have legalized recreational marijuana and the 28 states and the District of Columbia where medical marijuana is legal.

“There’s a different balance between the federal government and Indian tribes and the federal government and the states,” Capecchi said.

Nevada is still getting its enforcement footing after recreational marijuana became legal Jan. 1. Voters approved allowing adults to possess and use up to an ounce of pot, but consumption isn’t allowed in casinos or public places.

Bogden said a 2013 Obama administration directive that was seen as relaxing enforcement on tribal lands in states where pot is legal might have been misinterpreted.

Pot is still illegal in Indian Country and on federal land, he said.

The sentence in his letter to the tribe was underlined, along with the warning that “federal investigation and prosecution may still be appropriate.”

That was enough to prompt the tribe to declare that its police and event security won’t allow smoking, selling or transporting marijuana at its festival grounds near its fireworks stand, liquor outlet and smoke shop just off Interstate 15.

“We hope that attendees enjoy themselves and comply with applicable law,” Darren Daboda, chairman of the tribe with about 350 members and a sprawling 112-square-mile reservation, said in a statement.

The festival is modeled after a Cannabis Cup event held since 1988 in Amsterdam, which now has offshoots in pot-friendly states including Washington, California, Oregon, Colorado and Michigan.