Nevada rancher and states' rights advocate Cliven Bundy said Saturday that contract researchers for the federal Bureau of Land Management had no business being on rangeland where he grazes cattle, but he denied he or his supporters fired gunshots near them.

Three employees of a nonprofit Nevada organization told authorities they were monitoring water sources in the Gold Butte area, about 100 miles northeast of Las Vegas, on June 5 when they were approached by two men who asked what they were doing.

The researchers quickly left after six shots were fired later that night near their camp in an area that's being considered for federal protection as a national conservation area. There were no injuries.

Las Vegas police are investigating the incident. Bureau of Land Management officials have declined comment beyond a statement saying the shooting prompted them to take unspecified safety precautions in the area to protect is employees and contractors.

The incident follows a tense standoff in April 2014 between Bundy and the bureau after a federal judge authorized the agency to remove his cattle from public land. Bundy, who does not recognize the authority of the federal government, stopped paying grazing fees over 20 years ago and owes more than $1 million.

The confrontation pitted federal officers against heavily armed states' rights advocates who had converged on the Bundy ranch to halt the roundup of his cattle. The Bureau of Land Management backed off, citing safety concerns. It allowed Bundy supporters to release 380 cattle from pens that had been collected.

Bundy said he and his son, Ryan, were checking a water source when they met the three employees on a remote dirt road June 5, but he did not learn about the shooting and that they were researchers until reading a newspaper story nearly a week later.

"I asked them what they were doing, and they said they were looking for an area to set up camp. We just greeted them and welcomed them," Bundy said.

Thinking they were campers, the Bundys returned to their ranch about 12 miles away near Bunkerville and did not notify any supporters of their encounter with the three, he said.

"That's the last we heard of them until we read about it in the newspaper," Bundy told The Associated Press. "None of my friends or supporters would have known about it ... No, we didn't fire those shots. We didn't go back to the area."

Bundy said he visited the area with a Las Vegas police sergeant on Friday, and found no evidence corroborating researchers' statements to authorities that someone in a vehicle drove up and fired three shots on two separate occasions about an hour apart. The shots were fired from roughly a third of a mile away from their camp.

Bundy said he became upset after learning the researchers were monitoring water seeps and springs in the area.

"Those things are my private property, and I don't want anyone monkeying with my property," he said. "It doesn't matter whether they're contractors or BLM officials, either way they're trespassing on my rights. We're not going to put up with this."

While Bundy insisted the land in question is owned by the state, federal courts have consistently ruled it's under the jurisdiction of the federal government.

Jerry Keir, executive director of the Great Basin Institute, said it's "total speculation" whether the shots were meant to intimidate his researchers. The incident cut short their work as the Bureau of Land Management told them not to return to the area, he added.