By Steve Gorman

LOS ANGELES, Dec 17 (Reuters) - Negotiators for shipping lines and terminal operators at 29 U.S. West Coast ports remain far from a deal with union dockworkers after seven months of contract talks, the companies said on Wednesday, again blaming the union for waterfront cargo slowdowns.

The Pacific Maritime Association (PMA) statement came a day before the companies were slated to resume face-to-face bargaining with the International Longshore and Warehouse Union, representing 20,000 West Coast dockworkers in the talks.

The two sides huddled separately on Wednesday, two days after the union furnished the companies a counter-offer to a new set of proposals delivered by management last week.

"We are awaiting their reply, and perhaps they will have a response to all or part of our proposal" when talks resume, union spokesman Craig Merrilees said.

Ninety union delegates from all 29 ports met on Monday and Tuesday in San Francisco and voted unanimously to endorse their negotiating team. Both sides had said ahead of the union caucus that they were making progress, albeit slowly.

The two parties have strictly abided by a news blackout on details of their talks or the issues at stake. But on Wednesday the PMA issued a short communique denying any "statements and rumors that our negotiations are 'close' to a final contract."

"Even after seven months of negotiations, we remain far apart on several issues, and the union slowdowns continue to disrupt the movement of cargo through the ports," the PMA said.

Management has repeatedly accused the union of trying to gain bargaining leverage by orchestrating chronic cargo backups plaguing several West Coast ports since mid-October, most notably at the ports of Los Angeles and Long Beach - the nation's two busiest container cargo hubs.

Union officials dispute this. They point instead to other factors port officials cite as the main causes of gridlock. Chief among them is a shortage of tractor-trailer chassis used for hauling cargo from ports to warehouses, a situation created when shippers decided to sell off their chassis to third-party equipment-leasing companies.

Port officials also point to record import levels, rail service delays and the advent of super-sized container vessels delivering greater cargo volumes all at once.

The port slowdowns, coming just after the peak holiday shipping season, have nevertheless rippled through the commercial supply chain.

On a conference call with analysts on Wednesday, FedEx Corp executives blamed West Coast port labor tensions for cargo backups they said have caused retail inventory shortages.

(Editing by Eric Walsh)