Following other reports that weekend talks between employers and unions ended without resolution, Toyota has responded that prolonging the lockout affecting US west coast ports could affect more of its North American vehicle plants, Reuters said.

Toyota last week stopped assembly lines at the New United Motor Manufacturing (NUMMI) plant in Fremont, California, a joint venture with GM that employs 5,000 to build the Toyota Corolla and Pontiac Vibe, among other models, and is one of Toyota's nine assembly facilities in North America.

"If this type of situation continues, other plants (in North America) may be affected," Toyota president Fujio Cho told a news conference, according to Reuters.

Earlier, the broadcaster CBS said on its website that talks between shippers and longshoremen collapsed late on Sunday, the fourth day of talks with no date set for resumption, as the ripple effect of the week-old West Coast dockworkers' lockout continued to spread throughout the nation's economy, at a cost of about a billion dollars a day.

A management spokesman told CBS that the talks were broken off indefinitely after the dock workers' union rejected the latest contract proposal from manufacturers.

CBS said that the Pacific Maritime Association presented a comprehensive proposal to the union, which would have made their members the highest paid blue-collar workers in America.

Analysts and business leaders are increasingly sceptical of a quick end to the labour dispute, CBS said.

Dock workers have been working without a contract since July and a key issue in the dispute is the effect on their jobs of the planned introduction of new technology such as electronic shipment tracking.