VANCOUVER -- The union representing SkyTrain workers has issued a 72-hour strike notice.

CUPE 7000 has issued the notice to the B.C. Rapid Transit Company after four days of mediation in which they say "no significant progress" was made on key issues after more than 40 days of bargaining.

“We are still committed to reaching an agreement at the table, and our committee will make itself available day and night, over the weekend, to reach a fair deal without any interruption of service,” said CUPE 7000 President Tony Rebelo in a statement.

The union says parties are still bargaining and an update will be issued at 11 a.m. Saturday. The workers have been without a contract since August.

If a strike were to take place, service would be impacted on the Expo and Millennium lines, but Canada Line and West Coast Express service would not be affected.

When asked about what form the job action might take, Rebelo did not specify whether it would be gradual or a full-scale walkout.

“At this point we don’t know,” he said. “We’re working on that and we’ll let everybody know at 11 o’clock tomorrow morning.”

In November, the union voted 96.8 per cent in favour of strike action. The union represents 900 SkyTrain workers including attendants, control operators, as well as administration and maintenance staff.

The union has previously said its key issues are wages, staffing levels, overtime and a sick leave plan.

The strike notice comes the day after unionized bus workers and SeaBus workers voted to ratify a new three-year collective agreement. Unifor had threatened to launch a full-scale strike if a deal wasn’t reached by midnight last Wednesday.

Rebelo denied that CUPE is replicating the strategy used by the bus and SeaBus workers in their recent negotiations.

“We’re not copying anybody. We’re just looking at what we need to do, and we felt that our members told us two weeks ago that they’re willing to do what needs to be done to get a fair deal,” he said. “We felt that since we hadn’t gotten anywhere in four days we needed to put the 72 hours’ notice in play.”

The president of the B.C. Rapid Transit Company, Michel Ladrak, released a statement saying BCRTC has been "working hard" to renew its agreement with the union.

"CUPE 7000 has now ended mediation and has given BCRTC 72 hours’ notice that it will be taking job action. The union has not informed BCRTC what form the job action would take nor when it might occur," Ladrak said. "While we are disappointed by this development, BCRTC and CUPE will continuing bargaining through the weekend. We are hopeful and committed to reaching a fair deal without disrupting the valuable service we provide to the residents of this region."