Image copyright AP Image caption David Sweat (left) was serving life, while Richard Matt has a 25-year sentence

A female prison worker smuggled tools to two New York inmates before they escaped, according to prosecutors.

Joyce Mitchell, 51, gave hacksaw blades and drill bits to convicted killers David Sweat and Richard Matt, according to US media reports.

She is a workshop instructor at the Clinton Correctional Facility in Dannemora, northern New York.

A huge manhunt using hundreds of officers is now in its seventh day, stretching to Vermont and Canada.

"We continue to obtain information from her to try to get the understanding from her of why she helped these two individuals", said prosecutor Andrew Wylie.

She also planned to be the pair's getaway driver, but changed her mind at the last minute, investigators say.

Image copyright AP Image caption Police are searching hundreds of holiday homes in New York and Vermont

Image copyright AP Image caption The search area contains swamps and biting insects

Mr Wylie told CNN that Mrs Mitchell's husband, Lyle Mitchell, is also being investigated to determine if he played a role in the breakout.

Friday began the seventh day of the search for Matt, 48, and Sweat, 34, who broke out of 170-year-old prison with power tools.

The convicted murderers cut through brick and steel to crawl through an underground pipe on Friday night, and emerge from a manhole outside of the prison's 40-foot walls.

New York's governor has said any prison workers found to have helped two killers escape a week ago will find themselves being convicted.

Andrew Cuomo said: "If you do it, you will be convicted, and then you'll be on the other side of the prison that you've been policing, and that is not a pleasant place to be."

Image copyright Getty Images Image caption The pair climbed up through a manhole in their escape

Mrs Mitchell's son Tobey told NBC she checked herself into a hospital with chest pains on Saturday and would not have helped the inmates escape.

Mr Wylie, a district attorney, said that within the past 12 months Mrs Mitchell had been investigated for a suspected relationship with prisoner David Sweat.

Hundreds of employees and construction contractors have been investigated to determine if they provided the power tools.

Over 800 police officers are searching swampland nearby where the prisoners are thought to have spent a night.

Police dogs picked up a scent on Thursday, providing authorities with their strongest lead so far.

Food wrappers and a footprint were discovered several miles from the prison.

New York police say they have received over 700 leads over the past week.

Image copyright Reuters Image caption Authorities released pictures of the escapees' tattoos

Image copyright AP Image caption The escapees left a taunting note to prison authorities

The manhunt in northern New York and surrounding areas has included campsites and boat slipways in neighbouring Vermont.

Homeowners are being asked to remain at home with doors and windows locked, and to leave outdoor lights on overnight to aid investigators with the search.

Schools and roads remain closed.

Matt was convicted of the kidnap, torture and dismemberment of his former boss, whose body was found in pieces in a river.

Sweat was serving life for his part in the killing of a sheriff's deputy who witnessed stolen guns being handled.

5 June: David Sweat and Richard Matt escape from Clinton Correctional Facility in Dannemora

David Sweat and Richard Matt escape from Clinton Correctional Facility in Dannemora 6-7 June: Possible sighting of pair in Dannemora

Possible sighting of pair in Dannemora 9 June: Search focuses on Willsboro area after another possible sighting

Search focuses on Willsboro area after another possible sighting 10 June: Police close off Route 374 between Dannemora and Cadyville and search expands to neighbouring Vermont

Police close off Route 374 between Dannemora and Cadyville and search expands to neighbouring Vermont 11 June: Police dogs find food wrapper and footprint at suspected camp site near Dannemora

Police dogs find food wrapper and footprint at suspected camp site near Dannemora 12 June: Investigators announce that Joyce Mitchell, a prison worker, provided tools used in the break out

Image copyright Reuters Image caption Over 500 police are searching in New York