The FBI Tuesday added $250,000 to the reward offered for information leading to the arrest of Alan "Monte" Pilon and Jason McVean, the suspected cop killers whose run from police has resulted in a a 47-day manhunt across the rugged terrain of the Four Corners region.

The FBI special agents in charge, Frank A. LoTurco of Denver and David Tubss of Salt Lake City, announced the reward increase at a news conference in Denver Tuesday afternoon.Earlier the FBI had committed $50,000 in reward funds, but increased that amount to $150,000 per suspect Tuesday. The total reward now sits at close to $600,000 with Colorado state and local monies.

Profiles of the two men, including pictures and computer-altered images of them, have been added to FBI Internet web sites, LoTurco said. In addition, Colorado agents have set up a command center in Cortez, Colo., to receive information about the fugitives.

Pilon and McVean are wanted on both federal and Colorado state warrants for the May 29 slaying of Dale Claxton, a Cortez police officer gunned down while following the two men and Robert Mason, who were in a stolen water truck.

In a pursuit following the shooting, the three suspects also shot and wounded two Montezuma County, Colo., deputy sheriffs. As the manhunt progressed, they also attempted to shoot a U.S. Park Service employee near the Hovenweep National Monument, and on June 4 shot and critically wounded San Juan County deputy sheriff Kelly Bradford about four miles east of Bluff.

Mason, 26, of Durango, Colo., shot and killed himself after wounding Bradford.

But Pilon and McVean have continued to evade police, successfully using the dense vegetation of the San Juan River bottom and its surrounding cliffs as a hideout. At one point, more than 400 officers from 51 different police agencies were actively involved in the search.

Police have used foot patrols, search dogs, night vision equipment, helicopters, a tank and even attempted to burn up the river bottom's vegetation in an effort to find the men, but to no avail.

The cost of the manhunt, which continues to mount, is currently believed to be in excess of $1 million among all the agencies in-volved.

The fugitives should be considered "armed and extremely dangerous," LoTurco and Tubbs said Tuesday. Numerous explosive devices have been recovered during the search and have been linked directly to Pilon and McVean.

Cortez Police Chief Roy Lane cautioned bounty hunters from searching for the two men.

"We have had some bounty hunters and they are a concern to us. There's a concern we're going to get somebody else killed or hurt. This is some of the most treacherous country I've been in," he said.

Lane said the search will continue until the two men are captured.

"These people have to be arrested before they hurt or kill someone else," he said.

LoTurco said the reward money may bring someone forward with more information, but the FBI is not ready yet to put the two on the agency's 10-most-wanted list.

Lane said he thinks the two men are still in southeastern Utah.

"My gut tells me, and that's all it is, that they're going to stay in that area," he said.

Authorities, meanwhile, suspended their search to allow law enforcement officers time to re-evaluate and rest.

Anyone with information about the two men or who may have seen them should contact the FBI's Cortez command post at (970) 564-1749 or toll free at (888) 324-4310.