Warehouse workers and drivers at United Natural Foods Inc.’s Auburn warehouse have been without a contract since late August, at which time UNFI began a campaign against its workers, the union claims.

A total of 163 drivers and warehouse workers, employed at UNFI, went on an unfair labor practice strike Dec. 10. The union held a three-day strike to protest working conditions, followed by an unconditional return to work. Although UNFI agreed to the return, it then rescinded its offer and refused to allow the Teamsters back, permanently replacing 72 union members, the union claims.

The company said it had to hire some permanent replacement workers after members of Local 117 walked out.

The union returned to the picket line Dec. 13.

The National Labor Relations Board is investigating UNFI’s unfair labor practices actions, the union said.

UNFI is a distributor for natural food cooperatives in the Northwest.