TORONTO — The union representing about 4,100 Air Canada employees says it has suspended contract talks with the airline over shift trading issues.

Unifor says negotiators suspended talks on a new contract for customer sales and service agents after Air Canada released planned changes to shift trading rules.

The union says the airline cited concerns about reporting of hours worked, and health and safety issues, as reasons for the changed rules.

Unifor calls the new restrictions “unnecessary.”

A spokesman for Air Canada said in an email that “the shift change process is being modified to ensure compliance with federal regulations.”

Unifor said in a release Wednesday that the negotiations had been progressing, but halted them when the negotiating committee saw “the extent of the company’s intentions.”

“These are important issues that due to the timeline take precedence over bargaining,” Unifor spokesman Darryl Bink said in an email Wednesday night. “We need to work through them before proceeding further with negotiations.”