A 64-year-old MTA worker was slashed across the neck late Monday night inside a Brooklyn subway station.

Police say it happened around 10:39 p.m. inside the tunnel between the Franklin and Nostrand Avenue stations on the 3 line in Crown Heights.

The worker, who is a track maintainer, told investigators he noticed a man walking on the tracks the wrong way.

A police source told News 12 that the worker used his flashlight to stop trains twice and tried to guide the man off the tracks. That’s when he suddenly felt a slash across his neck from something sharp.

He never saw what the attacker used.

The worker fought back with his flashlight, climbed onto the catwalk and then boarded a train that carried him to Nostrand Avenue, where police and EMS met him.

TWU Local 100 President John V. Chiarello called the assault “yet another unacceptable attack” – saying it shows even track workers who don’t deal directly with riders aren’t safe.

“Every single day a transit worker is assaulted. It’s just getting worse and worse," said John Chiarello, president of TWU Local 100.

He was taken to NYC Health + Hospitals/Kings County and treated for a neck wound. He is in stable condition.

"Something like this shouldn't happen for our employees, they should be able to come in in the same condition and go home in the same condition," said Demetrius Crichlow, MTA New York City Transit president.