MONTREAL — Unifor says DHL Express Canada locked out workers just after midnight today as the two sides failed to reach a contract deal, injecting more labour turmoil into the country's parcel delivery market.

The union, which represents 2,100 truck drivers, couriers and warehouse workers across seven provinces, says they went on strike in response at 11 a.m. ET.

Unifor says the German-owned carrier is proposing to change the driver pay system and planning to use replacement workers before legislation banning them comes into effect on June 20.