New York City landlords found to be illegally harassing tenants will face up to a $5,000 fine under a package of tenant-protection bills signed into law Wednesday by Mayor Bill de Blasio.

De Blasio signed off on 15 measures — approved by the City Council earlier this month — at a ceremony in Manhattan.

He said the new laws aim to “crack down on tenant harassment,” especially among low-income residents and elderly renters who are increasingly being pushed out of their apartments by landlords seeking higher-paying tenants.

Three other related measures will be signed into law at a town hall in Brooklyn Wednesday night, according to the mayor’s schedule.

“We will not hesitate to crack down on abusive landlords,” de Blasio told an audience of elderly residents and affordable-housing activists at the Hargrave Senior Center on Manhattan’s Upper West Side.

The mayor called tenant harassment “among the most malicious side effects of New York City’s economic boom.”

The new set of laws increases the minimum harassment fine levied on landlords from $1,000 to $2,000, and increases the penalty to $5,000 for landlords who have been previously cited for tenant harassment in the past five years.

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The measures also expand the city’s definition of tenant harassment to include calls and visits by the landlord at “unusual hours.”

The bills also look to prevent landlords from prolonging construction and demolition projects in an effort to pressure tenants out of their apartments. The city’s Department of Buildings will issue completion deadlines when landlords seek building permits for projects in occupied buildings, and will increase inspection of construction and demolition projects in occupied buildings.

The building department will also establish an Office of the Tenant Advocate to handle harassment complaints.

Councilman Antonio Reynoso (D-Brooklyn), who sponsored three of the measures said “the use of construction in occupied buildings” has been “a common tactic” used to displace low-income tenants from their apartments.

“These bills will give the city the tools it needs to crack down on this practice and to help stabilize our neighborhoods and protect tenants,” Reynoso said in a statement.