The Halifax port is seeing a large upswing in container traffic due to a labour dispute at the Port of Montreal. (CBC)

The Port of Halifax is receiving dozens of requests from ships trying to avoid the labour dispute at the Port of Montreal, but the trucks and trains required to reroute through Nova Scotia may not be able to meet the demand, says the head a container terminal.

Halifax has no problem handling extra ships — the bottleneck is with the containers they're unloading.

At 20 million tonnes a year, Montreal normally handles nearly four times the volume Halifax receives, and the containers require rail and road transportation to reach customers such as Home Depot and Shoppers Drug Mart.

Port authority officials have said Halifax had been running at one-third capacity and can handle the extra work, but a key figure at the port has concerns.

"It's an insurmountable problem, I believe, for the shipping lines, the terminals and CN," said Calvin Whidden, general manager of Cerescorp, one of two container terminals serving the Halifax port. "I think the mountain is too big to climb very quickly."

The Maritime Employers Association locked out 850 Montreal longshoremen on Monday in a dispute over a new collective agreement. But on Thursday night negotiators for the employers group and the union representing the longshoremen reached a tentative deal to reopen the port Saturday.

Whidden said his phone has been ringing off the hook since the Montreal lockout began. The first diverted ship arrived Tuesday morning in Halifax.

CN Rail brought in two additional trains Wednesday to move stacks of containers that had been diverted from Montreal to Halifax, raising the number of trains a day to three from one.

"There's every effort now, it appears, that all shipping lines calling the Port of Montreal want to come through Halifax," Whidden said. "The requests and the attempts to try and help our customers out is taking us to the extreme."

It's unclear how long Halifax will have extra business from the dispute.