The 108 employees in charge of refueling planes at Montreal's Trudeau and Mirabel airports may go on strike Dec. 31, if no agreement is reached with their employer, Swissport, by then.

On Saturday, the International Association of Machinists and Aerospace Workers said 90 per cent of its members rejected the employer's last offer.

"They're not in the habit of going on strike or threatening to go on strike. But the membership is quite firm,'' union spokesperson Frank Saptel told The Canadian Press.

"Both parties need to talk and hopefully they'll get somewhere.''

The employees are responsible for refueling up to 500 aircraft per day and will go on strike if no agreement is reached by noon on Dec. 31. If that should happen, Swissport said it has established a contingency plan to ensure the supply of aircraft.

In the event of a walkout, Swissport Canada may also call on executives to maintain activities.

Mediation started up again Saturday afternoon, with salaries and work-life balance as the main points of contention between the employer and workers, who have been without a contract since August.

"The ball is in the employer's court and we need its help,'' union local president Peter Tsoukalas said in a statement.

Swissport Canada is the only supplier of fuel for airlines operating out of Trudeau and Mirabel airports.

A strike would cause "minimal disruption'' and air traffic would, for the most part, "continue as normal,'' Swissport said.

The employees threatening to strike include refuelling personnel, machinists, dispatchers, maintenance workers and mechanics.

Aéroports de Montréal said it is following the situation closely and "hopes YUL passengers won't have to pay the price for this conflict."