Negotiators have reached a tentative agreement to end a week-long strike crippling the key US ports of Los Angeles and Long Beach, Los Angeles Mayor Antonio Villaraigosa said. The announcement, made on the mayor's official Twitter account late Tuesday, came after a federal mediator was called in to try to end the standoff over the ports, which handle 40 percent of US maritime imports, mainly from Asia.

The mayor did not immediately provide further details about the agreement. The strike by clerical workers at the key US transport gateway, which constitutes the world's seventh biggest commercial harbor, has been costing billions of dollars to the local and wider US economy. The White House said Monday it was monitoring the standoff closely, and earlier Tuesday Villaraigosa said the two sides had agreed to federal mediation, after he spent the night in negotiations himself. The mayor said he had called Federal Mediation and Conciliation Service Director George Cohen by phone and asked him to send a mediator.

Copyright Agence France-Presse, 2012