Talks were yesterday continuing to avert potentially massive disruption to the US's trade with Asia as a key contract between dockworkers on the US Pacific Coast and their employers neared expiry.

The end of the last contract between the Pacific Maritime Association and the International Longshore and Warehouse Union in 2002 eventually led to a 10-day lockout of workers by port employers that is estimated to have cost the US $15bn.

Although the contract negotiated then expires at 5pm Pacific Coast Time today, there has still been no agreement on a new contract or on interim arrangements to stand until one can be agreed.

Among the ports that could be affected by any disruption are the twin ports of Los Angeles and Long Beach, which together handle 40 per cent of the US's container imports. The Pacific North West ports of Seattle and Tacoma are also major gateways, particularly for goods heading to the Midwest by rail.

The two sides announced on June 17 that they had reached a preliminary agreement on health and welfare benefits but the parties have since made no further announcements. One major sticking point is likely to be the introduction of labour-saving technology to improve efficiency at the ports, which are less advanced than in many other parts of the world.

The ILWU said that talks were being held in a constructive atmosphere very different from that in 2002, when employers initially extended the existing contract, but then locked workers out.

The Pacific Maritime Association said its focus continued to be to keep the ports open and functioning smoothly.

The two sides could agree to extend the contract to continue talks, but there are no signs so far of that happening. The unions could also call a halt to work on the expiry of the contract, although that looks unlikely.

"There are options that may be legally open but not pursued," the ILWU said.