Striking harbor clerks who work key California ports reached a deal with management Wednesday, ending a strike that had lasted more than a week.

Los Angeles Mayor Antonio Villaraigosa, appearing with representatives from both labor and management, announced a deal had been reached after hours of negotiations.

"I am pleased to announce that an agreement has been reached between labor and management that will bring to an end the eight-day strike that has cost our local economy billions of dollars," Villaraigosa said. The terms of the agreement were not immediately known.

The 800 clerks represented by the International Longshore and Warehouse Union had been on strike against the Los Angeles/Long Beach Harbor Employers Association, which represents management for the shipping lines and cargo terminals.

Estimates from management and retailers are that the strike was costing the nation's economy up to $1 billion a day. Tens of thousands of truckers, railroad, warehouse and other support workers were also temporarily out of work because the strike has stopped the flow of goods they normally handle.

Over the weekend, customers of the shipping lines, including major retailers, asked the White House to intervene and seek a court order forcing the clerks back to work during an mediated cooling off period. But when asked about that request at a daily briefing Monday, White House spokesman Jay Carney refused to say whether the Obama administration would consider intervening.

The National Retail Federation said Wednesday it was pleased with the end of the strike.

"We now hope that America's retailers and other businesses who rely on the ports can quickly recover from this shutdown," said Jonathan Gold, , vice president of supply chain and customs policy for the retail group. "We now hope the parties on the East Coast can reach agreement before their contract extension ends at the end of the month so we don't have to go through a similar situation impacting all container ports along the East and Gulf coasts at the start of the new year."

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A federal mediation team was dispatched to the scene, arriving Tuesday. Almost as soon as they arrived at the negotiations, it became clear management and workers were close to reaching a deal.

While the clerks don't actually handle the cargo, the 10,000 dock workers who do move the containers on and off ships had refused to cross the clerks' picket lines, effectively shutting down container operations at the nation's busiest ports.

The International Longshore and Warehouse Union charges that employers are trying to outsource good paying union jobs. Its members have been working without a contract since July 2010.

The group representing management disputed the claim that it is trying to send work elsewhere, saying in a statement that it is offering the union guarantees against layoffs. But it said the union's demand would make its operations less efficient. It would require them to hire unionized employees even though there is no business need for those workers, and place restrictions on customers entering data and tracking shipments electronically.

-- CNNMoney's Chris Isidore contributed to this report