The NYPD has enlisted metro-area truck-rental agencies to report suspicious renters to police in the aftermath of Monday’s deadly truck attack on a Christmas market in Berlin, New York City Mayor Bill de Blasio said Tuesday.

“The NYPD went back to a number of companies in the last 24 hours to check in and to check for anything suspicious,” de Blasio said Tuesday at an unrelated news conference. “Obviously, so far nothing has been brought up.”

Asking rental agencies to be anti-terrorism tipsters — a long-standing NYPD program to thwart terrorism — is one way the city hopes to avert attacks on large crowds and high-profile targets like the markets and Trump Tower, home of the president-elect, the mayor said. Heavily armed police officers, restrictions on truck travel near the tower and random police searches of commuters entering the subway system are other tactics.

The Islamic State has encouraged lone-wolf attackers to rent trucks to kill or harm people by driving into crowds, and on Tuesday the group claimed responsibility for Monday’s attack.

After the truck in Berlin rammed the market packed with tourists and locals outside the Kaiser Wilhelm Memorial Church near Berlin’s Zoo station — killing a dozen people and injuring nearly 50 others — the NYPD sent more police to patrol the city’s Christmas markets.

NYPD officers patrol near the Christmas tree at Rockefeller Center, Tuesday Dec. 20, 2016. Police across the New York metro area heightened vigilance after a truck crashed Monday into a Christmas market in Berlin, Germany, killing 12. Photo Credit: AP / Bebeto Matthews

New York City is home to dozens of Christmas-market events, the biggest of which are at Bryant Park, Columbus Circle, Grand Central Terminal and Union Square, according to Marketsofnewyork.com.

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“If any New Yorker sees anything suspicious around one of these Christmas markets, we need to know right away,” de Blasio said.

NYPD representatives, as well as their counterparts in Nassau and Suffolk counties, have said there are no known threats for the area, but the departments are increasing patrols just in case.

A Nassau police spokeswoman said her force has put more officers in shopping malls, mass-transit corridors, public gathering places and “near critical infrastructure.”

“Social media outlets will be intensely monitored,” she said.

Heavily armed NYPD officers stand guard at the Columbus Circle Holiday Market on Tuesday, Dec. 20, 2016. Police across the New York metro area heightened vigilance after a truck crashed Monday into a Christmas market in Berlin, Germany, killing 12. Photo Credit: Getty Images / Drew Angerer