An NYPD detective has been busted by the feds in a months-long string of robberies, sources said Tuesday night.

Federal agents collared Detective Kyron Collins, 39, about 9 a.m. Monday after a probe by the NYPD's Internal Affairs Bureau, sources said.

According to court documents obtained by WPIX 11, Collins and two others used a gun, a knife and even bogus search warrants along with his NYPD shield in a string of robberies that began in October 2010.

The crooks robbed "individuals in contraband cigarettes" and others at various locations in Manhattan and the Bronx, the papers show.

On July 26, Collins allegedly swiped $7,000 in cash from under a victim's mattress, the papers show.

Surveillance videos and cell phone records later linked the trio to the crimes.

Collins, a 16-year vet assigned to the 52nd Precinct in the Bronx, was charged with one count of robbery.

A relative declined to comment on Collins' arrest Tuesday night