A potential strike by about 800 airport security workers in Atlantic Canada has been delayed by the federal labour minister asking for a ruling on whether they provide an essential service.

'Why would anybody negotiate knowing that the federal government is going to step in and give them what they want?' — Lawrence McKay, United Steelworkers Union

The workers are employees of Securitas Transportation Airport Security, which has the contract for airport security at 17 airports in the four Atlantic provinces.

Federal Labour Minister Lisa Raitt has asked Canada Industrial Relations Board to determine if the security workers provide an essential service.

"I have asked the CIRB to review the situation to ensure that the health and safety of the public would not be affected by a work stoppage," Raitt said in a news release.

The security staff will have to maintain their normal work activities until the Canada Industrial Relations Board makes its decision. The intervention has frustrated the United Steelworkers Union.

"As a union we have to be able to put some pressure on the company in order to get a fair contract," said Lawrence McKay, the union's area coordinator.

"What our problem [is], now that Lisa Raitt has stuck her nose in it, is that the company's not going to be interested in going back to the bargaining table. They know they're in the same position as Canada Post was in, they know they're in the same position that Air Canada was in," he said.

"So why would anybody negotiate knowing that the federal government is going to step in and give them what they want anyway?"

Dispute over strike staffing levels

McKay said the union had been working on an essential-services agreement with Securitas. The union wants 80 per cent staffing levels in the event of a strike, something it says has been allowed at other Canadian airports.

With the current contract ending Wednesday, the workers could have walked off the job as early as Thursday. The union says a ruling from the Canada Industrial Relations Board could take two to four weeks.

Negotiations between the United Steelworkers Union and Securitas broke down late in September. Members voted almost unanimously to strike on Oct. 5.

Securitas spokeswoman Stephanie Spruston told CBC News they would not discuss the details of the negotiations. But the company did provide a statement.

"[Securitas] is seeking 100 per cent essential services coverage, while the union is seeking 80 per cent coverage, in the event of labour disruption," she said.

"While it is always preferable for the company and union to come to an agreement on essential service levels before going to the Canada Industrial Relations Board, given that Securitas is seeking 100 per cent coverage, the issue will likely be decided by the CIRB."

Justine Abel, director of case management services for the CIRB, said it takes 50 days on average to reach a decision in such situations.