New York City Mayor Bill de Blasio (D.) used a NYPD counterterrorism plane to travel between the city and Montreal, where he is taking a vacation.

The plane has sensors for detecting radioactive material from so-called dirty bombs and is not normally used to fly the mayor, the New York Post reports, but de Blasio’s office confirmed it flew him from Montreal to Westchester County Airport in New York on Thursday.

"NYPD is transporting him in their plane," de Blasio spokesman Eric Phillips said.

De Blasio was in Montreal when the plane came to pick him up and take him to the memorial for slain NYPD detective Miosotis Familia. He took the same plane back to Montreal from Westchester to continue his vacation.

One source told the Post that the use of the plane was "excessive."

"It is very unusual to go on an international flight to go pick up the mayor," the source said. "I think it’s excessive, because that wasn’t what that plane was designed to do. It’s designed for counterterrorism measures. To go to Canada to get the mayor? It’s excessive."

The NYPD said its policy is not to "comment on specific details regarding the protection of elected officials" but did say the flight was planned so as to avoid affecting other operations.

"Careful consideration is made to ensure that the work of the security detail has no impact on other NYPD operations," a spokesman said.

The plane, a Cessna 208 Caravan, normally takes two-to-three hour flights starting and terminating at MacArthur Airport on Long Island. It cost the department about $3 million, and one source told the Post that its use for the mayor Thursday must have cost thousands of dollars.