The union representing grain workers at terminals in Metro Vancouver says it has served the employer with a 72-hour strike notice.

The Grain Workers Union Local 333 says in a notice posted to Facebook that it served the notice at 7 a.m. Saturday, with job action to start Tuesday.

It says the union's bargaining committee made the decision after the Vancouver Terminal Elevators Association "invested very little effort" during negotiations last week, and it's now up to the employer to present a proposal for a new contract.

The union says it provided the employer with a "comprehensive package" last Thursday and the next day the association indicated it had no counter offer.

A statement issued by the Vancouver Terminal Elevators Association says it concluded conciliation with the union with assistance from the Federal Mediation and Conciliation Service on Aug. 26.

But it says it couldn't come to an agreement on a new contract and the union has been in a legal strike position since last Tuesday.

It says affected operations include Viterra's Cascadia and Pacific Terminals, Richardson International Terminal, Cargill Limited Terminal, G3 Terminal Vancouver and Alliance Grain Terminal, all located in Vancouver and North Vancouver.