By STEVEN DUBOISPORTLAND, Ore. (AP) â¿¿ A union local has filed an unfair labor practice claim against the owner of a Pacific Northwest grain terminal that locked out employees after alleging a worker sabotaged equipment. The charge filed Monday against United Grain Corp. by Local 4 of the International Longshore & Warehouse Union contended the lockout was an extreme, illegal response. The local represents roughly 200 workers who load grain and other cargo at the Port of Vancouver, Wash. More than a quarter of all U.S. grain exports move through Pacific Northwest grain terminals, so any labor problem at the ports is a concern for farmers shipping their corn, soybeans and wheat to customers in Asia. United Grain locked out longshoremen on Feb. 27 after saying Todd Walker, a member of the union bargaining team, was responsible for damaging company equipment in December. In its filing with the National Labor Relation Board, the local said the company can't punish all the workers for the alleged act of one person. "This constituted loss of employment based on anti-union animus, and a sweeping unilateral change of terms and conditions of employment." the local said in the complaint. Late last year, United Grain was among three Northwest terminal owners that declared an impasse in negotiations with the ILWU and imposed a contract that included new, management-friendly workplace rules. United Grain said the sabotage occurred Dec. 22, just days before the impasse was declared. In a lawsuit filed against Walker, the company states he shoved a 2-foot-long metal pipe into a conveyor and poured sand into a gear box. Vancouver police are investigating. Walker has not been charged with any crimes. Union spokeswoman Jennifer Sargent said Walker is not available for interviews about the accusations or the lawsuit against him. United Grain was "disappointed but not surprised" by the unfair labor practices filing and will cooperate with the NLRB investigation, said Pat McCormick, a spokesman for terminal owners.