Ship lines and terminals on the West Coast are accusing the dockworkers union there of a continuing effort to hamper cargo movements.
The Pacific Maritime Association, which represents employers on the coast, issued a statement late Thursday saying the union was refusing to dispatch skilled workers to key Southern California yards where marine containers are loaded onto trains and trucks headed inland.
"Terminal congestion has been a mounting issue at Southern California port terminals due to a variety of factors, including a surge in cargo volume, shortage of chassis and rail cars, and insufficient numbers of truck drivers. Given these already congested conditions, the ILWU's refusal to fill critical yard crane positions makes an already difficult situation far worse," the 78-member PMA said.
Earlier in the week, the management group accused the union of staging a work slowdown at the ports of Seattle and Tacoma in the Pacific Northwest.
Read MoreWest Coast dock talks teeter
Dockworkers, represented by the International Longshore and Warehouse Union, have been working without a contract since July. The ongoing situation on the West Coast, which handles roughly 60 percent of the nation's containerized marine cargo, has been a source of worry for the nation's importers. Retailers are still bringing in some inventory for the holidays. Manufacturers rely on smooth connections through the coast to maintain time sensitive manufacturing schedules.
When contacted by CNBC, ILWU said workers are frustrated becauseemployers have delayed action on the port congestion problemsfor years and have delayed a resolution of the contract talks formonths.
A longshoreman working 1,600 hours a year—two-thirds of the longshore workforce—earns about $123,000, according to statistics from the PMA. Clerks make $147,000 and walking bosses (foremen) make $209,000 for similar kinds of hours. In addition, workers get a benefits package worth about $93,000 a year.