Traffic at nearly 30 West Coast ports is on the verge of "complete gridlock" and shipping officials have threatened to stop paying dockworkers if a contract deal is not reached soon.

Speaking at a press conference on Wednesday, Pacific Maritime Association CEO James McKenna said West Coast seaports, which handle some $1 trillion in trade per year, could shut down in the next five to 10 days and cripple U.S. trade with Asia. He said the organization is not considering a technical "lockout," but warned that the shipping system would inevitably bring itself to a stop if congestion persists.

PMA and the International Longshore & Warehouse Union have been working to negotiate new contracts since May. Nearly 20,000 dockworkers at 29 ports are impacted. PMA says ILWU has conducted slowdowns, walk-offs and other actions at key ports, aggravating congested conditions and disrupting cargo movement in a bid to influence the talks. He said productivity had dropped between 30 percent and 50 percent in recent months, crippling whole strings of vessels, in some cases. It's like "they're getting paid to grind us into the ground," McKenna said.

The union denied the claims and said the congestion crisis was "employer-caused."

IN-DEPTH

-- Karma Allen, CNBC