Los Angeles — Negotiators have agreed to a tentative contract covering West Coast dockworkers, likely ending a protracted labor dispute that has snarled international trade at seaports handling about $1 trillion worth of cargo annually.

The breakthrough came after nine months of negotiations that turned contentious in the fall, when dockworkers and their employers began blaming each other for problems getting imports to consumers and exports overseas.

Dockworkers union spokesman Craig Merrilees confirmed the agreement Friday evening. It must be approved by the 13,000-member International Longshore and Warehouse Union, which works 29 ports from San Diego to Seattle.

Talks began in May, and the prior six-year contract expired July 1. By November, agricultural exporters said some goods were spoiling before they reached market, and U.S. retailers said their products were stuck on the docks.