It’s the city’s dirty little secret.

Trash baskets are mysteriously vanishing from Big Apple street corners, and one Sanitation official says it’s a citywide problem caused by scrap-metal thieves.

The baffling basket cases are particularly plaguing the Upper West Side, City Councilwoman Helen Rosenthal told The Post.

She said residents recently reported containers missing along Amsterdam Avenue and Broadway in the low 70s and Central Park West in the 80s.

The lawmaker said the trash can “right in front of my office” on 87th and Columbus also “went missing.”

When Rosenthal raised the issue at her April 25 town hall meeting, Sanitation official Ignazio Terranova confirmed the community’s worst fears.

“You are 100 percent correct,” the community affairs officer told the nearly 200 people in attendance. “Baskets have been disappearing, not just here in Community Board 7, but we’re having this problem citywide. And it’s because the price of metal actually is really good right now, so people are stealing our baskets and bringing them in [as] scrap,” he said.

Of the city’s 23,500 litter baskets, the most common design is the steel wire-mesh container. It weighs 32 pounds and costs about $125 new.

Scrap yards last week quoted the going rate for the steel as between 5 ¹/₂ and 6 ¹/₂ cents per pound — or about $2 a can.

Joseph Giacalone, a retired NYPD detective sergeant and professor at John Jay College of Criminal Justice, wasn’t surprised by the reemergence of a cyclical crime trend and urged the NYPD and public to be “vigilant.”

“Stealing city-owned garbage cans for scrap is not something to be taken lightly and it’s a trend that needs to be nipped in the bud,” he said.

The Sanitation Department downplayed the trend, despite its own official revealing it.

Agency spokesman Vito Turso insisted in a written statement that “there are no ‘mysterious’ litter basket disappearances on the West Side or anywhere else in NYC.”

Litter baskets “are sometimes stolen, they are improperly relocated by neighbors from their assigned street corners (to mid-block), they are often removed by DSNY for special events or for NYPD security operations, and they are sometimes brought in for repair after being hit when locals place them in the street to steer drivers away from potholes or other unusual road conditions,” he said.

“We also remove baskets that are being abused and misused by local residents who illegally toss their household trash into them. (a $100 fine) But theft is NOT and has not been a serious issue.”

Turso said Sanitation annually loses “around 100 or so” of its baskets for “unknown reasons.”

The NYPD said last week it knew of no complaints regarding stolen baskets. Police officers from the 20th and 24th precincts attended the April 25 town hall.