Gatineau police cruisers were defaced with messages referring to stalled talks between the police union and the city. (CBC)

More than a dozen police vehicles in Gatineau, Que., were vandalized overnight Monday with messages in orange paint referring to a labour dispute between officers and the city.

Many of the 10 vehicles, including cruisers and vans, were brush painted with "3½" — an apparent reference to the number of years the Gatineau police have been without a contract.

The hood of one car was also painted with the words, "Bureau Maire Meprisant" (Marc Bureau is a contemptuous mayor). On the side of the vehicle, the French word for "pride," normally printed alongside "courtesy," "respect," and "integrity," was painted over.

A police spokesman said management ordered the vehicles taken off the road after they were informed of the vandalism. As of Tuesday morning, the defaced vehicles were parked in a gated police parking lot.

Roch Legault, president of the police union, did not deny that his members committed the vandalism.

He said it's their only means of expressing frustration with the city over its refusal to negotiate a new contract.

"We don't have the right to strike," he told CBC's French-language service Radio-Canada in French. "We face an employer who is recalcitrant, who is difficult, who is of bad faith."

Legault said union members are tired of waiting, as arbitration won't begin again until the fall.

However, Joseph De Sylva, Gatineau's deputy mayor, said there is nothing the city can do about that.

"We have the arbitrator and he's the one who will take the decisions," he said. That includes the timing of meetings, he added.

Gatineau's chief of police declined to comment.

Last July a dozen police cruisers were vandalized in a similar manner, and both city and union officials suggested the vandalism might have been committed by frustrated officers.

But neither the union nor the city ever confirmed officers were involved in last year's vandalism.

The officers' most visible act of protest during stalled negotiations has been to wear cargo pants and khakis instead of police-issue slacks.

With files from the CBC's Robyn Burns