RENO, Nev. - U.S. Bureau of Land Management officials said they agree with a Nevada sheriff's position that rancher Cliven Bundy must be held accountable for his role in an April standoff between his supporters and the federal agency.

Clark County Sheriff Doug Gillespie said Bundy crossed the line when he allowed states' rights supporters, including self-proclaimed militia members, onto his property to aim guns at police.

"If you step over that line, there are consequences to those actions," Gillespie told the Las Vegas Review-Journal. "And I believe they stepped over that line. No doubt about it. They need to be held accountable for it."

Bureau spokeswoman Celia Boddington, in a statement released Saturday to The Associated Press, said the agency continues to pursue the matter "aggressively through the legal system."

"There is an ongoing investigation and we are working diligently to ensure that those who broke the law are held accountable," she said, declining to elaborate.

The FBI declined comment Saturday on its investigation. Bundy did not respond to a request for comment.

The Bureau of Land Management said Bundy owes over $1 million in fees and penalties for trespassing on federal land without a permit over 20 years. Bundy, whose ancestors settled in the area in the late 1800s, refuses to acknowledge federal authority on public lands.

A federal judge in Las Vegas first ordered Bundy in 1998 to remove "trespass cattle" from land the bureau declared a refuge for the endangered desert tortoise. Bureau officials obtained court orders last year allowing the roundup.

Boddington disputed Gillespie's contention that the agency mishandled a roundup of Bundy's cattle 80 miles northeast of Las Vegas. The roundup was thwarted by Bundy and his armed supporters.

The bureau backed down during the showdown, citing safety concerns, and released about 380 Bundy cattle collected during a weeklong operation from a vast, arid range half the size of the state of Delaware.

Gillespie blamed the bureau for escalating the conflict and ignoring his advice to delay the roundup after he had a confrontational meeting with Bundy's children a few weeks before it began.

"I came back from that saying, 'This is not the time to do this,'" the sheriff told the Review-Journal. "They said, 'We do this all the time. We know what we're doing. We hear what you're saying, but we're moving forward.'"

Tensions further escalated early in the roundup after a video showed one of Bundy's sons being stunned with a Taser, Gillespie said. The video drew militia members and others to Bundy's ranch.

Boddington said the bureau planned and conducted the roundup in "full coordination" with Gillespie and his office.

"It is unfortunate that the sheriff is now attempting to rewrite the details of what occurred, including his claims that the BLM did not share accurate information," she said. "The sheriff encouraged the operation and promised to stand shoulder-to-shoulder with us as we enforced two recent federal court orders."

"Sadly, he backed out of his commitment shortly before the operation - and after months of joint planning - leaving the BLM and the National Park Service to handle the crowd control that the sheriff previously committed to handling," she added.