NEW YORK (AFP) - Hundreds of police officers closed in on Saturday on a convicted murderer who busted out of a maximum-security New York prison, a day after authorities shot dead his fellow escapee in a three-week manhunt.

Richard Matt, 49, was killed on Friday in the town of Malone, less than 16km from the Canadian border, and the net appeared to be closing on his accomplice David Sweat.

Police believe they have the 35-year-old Sweat, who was serving a life sentence without parole for murdering a sheriff's deputy in 2002, contained within a perimeter, CNN reported.

The duo, whom police described as dangerous and possibly armed, used power tools to cut their way out of their cells at the Clinton Correctional Facility before dawn on June 6 in a spectacular prison break likened to a Hollywood movie.

Matt's bid for freedom reached a fatal conclusion on Friday after he apparently fired at a passing camper van, with more than 1,000 policemen and agents in hot pursuit.

New York State Police Superintendent Joseph D'Amico did not say why Matt shot at the vehicle. But The New York Times quoted a source as saying he was attempting to carry out a carjacking.

Police found Matt, who was serving a sentence of 25 years to life for the 1997 kidnapping and dismembering of his former boss, near a cabin.

"We were able to get into the cabin, where we discovered the smell of gunpowder and realized a weapon had been fired," D'Amico told reporters.

"As we were doing the ground search in the area, there was movement detected by officers on the ground... A tactical team from Customs and Border Protection met up with Matt in the woods, challenged him, and he was shot dead by Border Patrol at that time."

Officers recovered a 20-gauge shotgun from Matt.