Unionized workers at Canadian Pacific Railway have turned up the heat at the bargaining table, serving 72-hour strike notice.

The company issued a news release Saturday saying that negotiations are continuing with the Teamsters Canada Rail Conference, who represent 5,000 Canadian Pacific employees.

The news release says the workers, who include conductors, trainmen, yardmen, locomotive engineers and rail traffic controllers, can walk off the job at 12:01 a.m. May 23.

The workers have been negotiating with CP since October to try to reach a new contract — the last one expired in January.

The union says CP is demanding major concessions on pensions, work rules and wages.

The company says if there is a work stoppage, it will "proceed with a safe and structured shut down of its train operations in Canada."

"CP believes the offer it has presented the union is fair and reasonable. We are willing to enter into binding arbitration or negotiation period extensions should an agreement not be reached at this stage," said Executive Vice President and Chief Operations Officer Mike Franczak.

"This would ensure the continued operations of freight and commuter trains on CP's Canadian Network for the benefit of our customers, communities we serve and the economy at large."