Protesters of a six-week armed occupation at a U.S. wildlife refuge in Oregon pleaded not guilty on Wednesday to charges of conspiring to impede federal officers policing the compound, a sign the long-simmering fight over federal control of land in the West is far from over.

Ammon Bundy and other anti-government protesters arrested in connection with the takeover of the Malheur National Wildlife Refuge in eastern Oregon appeared in U.S. court in Portland.

The tense stand-off with law enforcement drew international attention and prompted fears it would erupt in more violence.

RELATED: Accused Oregon refuge occupier cites devil, demands $666,666,666,666.66 in damages

"Ammon is very excited to move forward with his case and access and utilize his Constitutional rights to continue his mission," his lawyer, Mike Arnold said Wednesday. "He can do that within the confines of the court process."

Wednesday's arraignment came a day after FBI personnel finished combing the refuge for new evidence that could result in additional charges filed by prosecutors. Prosecutors will likely file a superseding indictment in early March that may add new "charges and defendants," court documents show.

Sixteen protesters pleaded not guilty to one conspiracy charge each, Arnold said. A status hearing was set for March 9.

Bundy and other defendants are accused of plotting to prevent by "force, intimidation, and threats" agents of the U.S. Fish and Wildlife Service from performing their duties, the indictment said.

RELATED: FBI discovers human feces at surrendered Oregon refuge site

In all, 25 people have been indicted over the occupation, Arnold said. Bundy, his brother Ryan, and others also face charges over a 2014 standoff near their father's ranch in Nevada.

The occupation ended on Feb. 11 when the final four protesters surrendered to authorities following a dramatic exchange with mediators.

The Bundy brothers and nine other protesters were arrested on Jan. 26 after a traffic stop. After a chase prompted by the traffic stop ended at a law enforcement roadblock, one of the protesters, Robert "LaVoy" Finicum was shot dead.

A grand jury indictment says the defendants brandished firearms and refused to leave the refuge, threatening violence against anyone who attempted to remove them, and warned a county sheriff of "extreme civil unrest" if their demands were unmet.

RELATED: Oregon locals distance themselves from extremist 'militiamen'

The Malheur takeover, the cost of which will likely run into the millions of dollars, was sparked by the return to prison of two Oregon ranchers convicted of setting fires that spread to federal property near the refuge. The occupation also was a protest over federal control over millions of acres of public land in the West.