LOS ANGELES >> The nation’s top labor official is bringing a clear message to dockworkers and their employers amid a contract dispute that has crippled international trade through West Coast seaports: Reach a deal — and fast.

U.S. Labor Secretary Thomas Perez held what his office characterized as "positive and productive meetings" Tuesday with both the dockworkers union and the maritime association representing companies that own, load and unload massive ships laden with U.S. exports and imports from Asia.

It was his first full day in San Francisco, which is home to both the International Longshore and Warehouse Union and Pacific Maritime Association, representing shipping lines that carry cargo and port terminal operators that handle it once ships dock. Perez renewed his efforts Wednesday, with political and economic pressure rising to get a contract and free cargo bottlenecks at 29 ports that handle about $1 trillion of trade annually.

As contract talks have stalled, so too has the flow of trade. Dozens of ships are anchored off Southern California, in San Francisco Bay and in Washington’s Puget Sound. They are waiting for dock space that is taking weeks to free up due to employers locking out workers or work slowdowns alleged by the companies.

Perez does not have legal authority to force an agreement, but outsiders hope he can resolve differences that a federal mediator could not.

The two sides already have reached tentative agreements on key issues including health benefits and what jobs the union can retain in the future.

And their wage proposals are not far apart. Under the prior contract, which expired in July, average wages exceed $50 an hour, according to the maritime association.

"While the parties have made tremendous progress, Secretary Perez stressed that it’s imperative the parties come to an immediate agreement to prevent further damage to our economy and further pain for American workers and their employers," the labor secretary’s office said in a statement Tuesday.

Spokesmen for the union and maritime association declined to comment, citing a media blackout.

The issue that brought talks to a stalemate is whether to change the system for arbitrating allegations of work slowdowns, discrimination and other conflicts.

The union is pushing changes that would let either side dismiss an arbitrator when the contract expires, typically after six years. Both sides would then have to agree on a replacement. Motivating the demand is a desire to replace the arbitrator who handles grievances in Los Angeles and Long Beach.

The maritime association wants to keep the current system, under which arbitrators effectively have lifetime appointments. The association has argued that reappointment pressure might cause arbitrators to sacrifice their independence because of worries they might offend one side and jeopardize their future.