Image copyright AP Image caption Gene Palmer has appeared before a judge on several charges, including promoting prison contraband

A US prison guard believed to have smuggled tools hidden inside hamburger meat to two prisoners who escaped a New York state jail has been arrested.

Gene Palmer is the second prison worker detained over the jail break. Joyce Mitchell has already been charged with aiding the escape.

The prisoners, Richard Matt and David Sweat, used power tools to flee the Clinton Correctional Facility.

A massive manhunt is still under way to find the pair, both convicted killers.

Mr Palmer has been held on bail, after appearing before a judge on charges of promoting prison contraband, tampering with physical evidence, and official misconduct.

His lawyer, Andrew Brockway, admitted his client delivered the meat but said he did not know it contained the tools, nor that the prisoners were trying to escape.

Image copyright Getty Images Image caption David Sweat (l) and Richard Matt are both convicted murderers

Image copyright Reuters Image caption Their escape from a high-security prison has been compared to a Hollywood film

"He did pass the hamburger meat. He shouldn't have done it. He apologised for it,'' said Mr Brockway, who added his client plans to plead not guilty.

Clinton County District Attorney Andrew Wylie said Ms Mitchell placed hacksaw blades and other tools inside the meat, before Mr Palmer took it to Matt and Sweat, who were interred in a section of the jail where prisoners can cook their own meals.

Meanwhile, officers are concentrating their search on a 75 sq mi (194 sq km) area of northern New York state.

Police found evidence the two men spent time at a hunting cabin near the prison, and it is believed they may be armed, given how heavily the area is stocked with weaponry.

"They are extremely dangerous, they're cunning," said New York State Police Major Charles Guess. "Why wouldn't they try to arm themselves immediately upon escape?''