BELLMONT, N.Y. - A maximum-security prison guard believed to have delivered tools inside frozen meat to two inmates before they escaped was arrested on Wednesday, authorities said.

Gene Palmer appeared before a judge in Plattsburgh on Wednesday night to face charges of promoting prison contraband, tampering with physical evidence and official misconduct. He was held on $25,000 bail pending arraignment Thursday. Defence lawyer Andrew Brockway said he will plead not guilty.

Inmates David Sweat and Richard Matt were reported missing from the Clinton County Correctional Facility in upstate Dannemora on June 6. Authorities say they cut through the steel wall at the back of their cells, crawled down a catwalk, broke through a brick wall, cut their way into and out of a steam pipe and then sliced through the chain and lock on a manhole cover outside the prison.

Prison employee Joyce Mitchell also has been charged with helping them escape. The prison tailor shop instructor has pleaded not guilty and remains in custody.

Clinton County District Attorney Andrew Wylie said Mitchell told investigators she smuggled hacksaw blades, a screwdriver and other tools into the prison by placing them in frozen hamburger meat. He said she then placed the meat in a refrigerator in the tailor shop where she worked and Palmer took the meat to Sweat and Matt, who were housed in a section where inmates are allowed to cook their own meals. The district attorney said the guard didn't know the tools were inside the meat.

Palmer had been placed on leave on Tuesday. At the time, his attorney Andrew Brockway told Plattsburgh television station WPTZ he was completely forthcoming during several hours of questioning on Saturday.

"I can 100 per cent confirm that he did not know they were planning on breaking out of the prison," Brockway said.

Searchers hunting for the escaped killers Wednesday were contending with steep slopes, thick woods, sticky bogs, biting bugs and the possibility that the pair on the lam from prison for 19 days is armed.

Police said they remain almost 100 per cent certain that Sweat and Matt spent time recently at a hunting camp about 32 kilometres west of the correctional facility near Owls Head. A hunter said he saw a figure bolting from the cabin on Saturday morning. But after days of intense searching with dogs and helicopters, police still had no substantiated sightings of Sweat and Matt.

The 194.25 square kilometres searchers focused on is on the northern edge of the sprawling Adirondack Park and includes woods so thick that visibility is only a few feet in some sections, authorities said. The woods also are dotted with hundreds of seasonal and hunting camps.

State police Maj. Charles Guess said Wednesday that authorities don't have confirmed evidence that a shotgun was stolen from the hunting cabin near Owls Head, but they've always assumed the escapees were armed. Weapons and ammunition are typically stored in camps, but not everyone keeps an inventory of their firearms, he said.

Guess said it was possible the pair left the area, but promised that the more than 1,000 officers involved would keep up the relentless search until the killers are captured.

"We don't want them to have a restful, peaceful night putting their head on any pillow," he said.

Sweat, 35, was serving a life sentence without parole for killing a sheriff's deputy. Matt, 48, was doing 25 years to life for the kidnapping, torture and hacksaw dismemberment of his former boss.