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SAN FRANCISCO (AP) — Mayor Ed Lee's effort to brand the city as the world's high-tech capital got a boost Monday as cloud-computing company Riverbed Technology Inc. announced its new downtown headquarters.

The company's move to the renovated 168,000-square-foot space from smaller offices nearby could bring more than 600 new tech jobs to the city, the mayor said.

Riverbed plans to move into its new offices in the city's coveted South of Market neighborhood in 2014. It has signed a 10-year lease.

The 168,000-square-foot space will expand the size of Riverbed's headquarters by more than 60 percent, which the company says will allow it to more than double its current San Francisco workforce of 500.

The news came a month after Lee announced another major San Francisco tech company, online customer relations software provider Salesforce.com, signed what he called the city's largest long-term lease in a decade for 400,000 square feet of office space. He recently said networking site LinkedIn Corp. would also be expanding its offices in the city.

Since his successful effort last year to persuade Twitter Inc. to stay in San Francisco, Lee has cultivated an image as a tech-friendly politician eager to present the city as a Silicon Valley alternative.

"We want companies to start here, stay here and continue to grow," Lee said at a briefing on the Riverbed deal.

Part of the attraction for tech companies could be a measure Lee signed into law in June capping the tax levied on stock options as part of San Francisco's unusual payroll tax — a measure some progressive politicians and unions complained was a giveaway to the wealthy. The city has also tried to capitalize on its cachet as a place where young programmers and designers would prefer to live over Silicon Valley's suburban environs.

Riverbed chief executive Jerry Kennelly said the city's concentration of potential hires played a big part in keeping the company in San Francisco.

"Every day it's a war for talent. We're all fighting to get the best and brightest," Kennelly said.

San Francisco's unemployment rate stands at 7.6 percent, below the national average and the third-lowest unemployment rate in California, as city officials say the number of tech jobs in the city nears levels not seen since the first dot-com boom.

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