A smoking-gun e-mail reveals in detail how NYPD cops were ordered to “sweep” homeless people from two subway stations ahead of Mayor de Blasio’s arrival Sunday — despite officials’ denials that the directive was given.

Two law-enforcement sources separately read to The Post a portion of the e-mail Monday to counter City Hall’s claims that the paper’s Page 1 account of the police action was “not true.”

The e-mail from the city’s Transit Bureau instructed NYPD officers from Transit District 30 to accompany Hizzoner during a rolling press conference — at which de Blasio denied responsibility for the crumbling subway system.

“Once the mayor arrives at the 4th Avenue station, he will board the N-B [northbound] ‘F’ train to the Jay Street-Metro Tech station. TD-30 officers are to escort the mayor aboard the N-B ‘F’ train from the 4th Avenue station to the Jay Street station,” the e-mail says.

“Before the mayor arrives at the 4th Avenue station, the officers are to sweep the station for homeless persons as well as the Jay Street station. There will be press at the 4th Avenue station.”

City Hall spokesman Austin Finan doubled down on denying the directive Monday, saying, “Once again, readers should know that these sources are refusing to provide their names because what they are saying is not true.”