The National Retail Federation (NRF) has renewed calls for the US government to intervene in a strike that has shut down most terminals at the ports of Los Angeles and Long Beach.

"As we enter day six of the strike, NRF is renewing its call for President Obama to intervene and and end this work stoppage," said NRF CEO Matthew Shay.

"The shutdown is already having a significant negative economic impact on retailers trying to bring in merchandise for their final push for holiday sales and will soon have an impact on consumers. 

"The work stoppage not only impacts retailers, but is also affecting their product vendors - many of which are small businesses - and other industries like manufacturers and agricultural exporters that rely on the ports.

"As the debate in Washington continues to focus on the state of the American economy and relief for middle-class consumers, a protracted strike will ultimately result in higher prices at the very time we can least afford it.

"This strike is now at the national emergency stage impacting industries far and wide. ‘Urging' both sides toward a solution is not the answer. The Obama Administration needs to show leadership and resolve to get the ports operational again and prevent any further economic damage."

The NRF said the two parties have been negotiating a contract on and off for over two years, and while issues have remained unresolved during these negotiations, it is critically important that the two parties remain at the table until a new deal is finalised.

"A 10-day lockout at the West Coast ports as a result of stalled negotiations in 2002 led to lingering supply chain disruptions and cost the US economy US$1bn for each day of the lockout. It took the ports a full six months to recover, and the strike had a profound impact on the retailers, importers, manufacturers, agricultural exporters and other affiliated industries that rely on the ports every day.

"An extended strike this time could have a greater impact considering the fragile state of the US economy," Shay said last week.

According to Reuters, the dispute has been triggered by 500 clerical workers at the ports, members of the Clerical Union Workers.

Their clout has been significantly strengthened because some 10,000 members of the International Longshore and Warehouse Union have supported them, refusing to cross their picket lines.

The action has effectively shut down 10 of the two ports' combined 14 container terminals.