VARENNES, QUE. -- Management at Jean Coutu is trying to reassure customers that it will still be able to distribute prescription drugs after it locked out nearly 700 employees at its warehouse near Montreal.

Jean Coutu runs the largest pharmaceutical distribution company in Quebec, and its warehouse in Varennes supplies prescription drugs to more than 500 outlets across the province.

Workers discovered they were locked out on Thursday morning; contract talks had stalled after months of negotiations. Issues like seniority and subcontracting are at the core of the negotiations.

The company claims its workers were breaking the rules.

"You have to understand, it follows illegal pressure tactics throughout the summer," said Marie-Claude Bacon, vice-president of public affairs and marketing at Group Metro- Jean Coutu.

Jean Coutu is a behemoth, holding an estimated 30 per cent of market share for pharmacies in Quebec. An extended labour conflict has the potential to disrupt the distribution of prescription drugs.

Management at Jean Coutu said they have a contingency plan to continue the shipments of medication to outlets across Quebec, but union leader Audrey Benoit said she isn't sure the company will be able to pull it off.

"We are 680 people that work day and night to be able to give all the Quebecers all they need. They tell me they have enough people? I don't think so," she said.

Bacon said it's doable.

"We have management that will be in the warehouse, preparing orders to make sure they're supplied with the medication for our network," she said.

Picketers prevented trucks from entering or leaving the building in Varennes Thursday.

The company refused to say if it would seek a court order to clear the entrances and exits.

Both sides have agreed to meet with a conciliator on Sunday to find a compromise.