SAN FRANCISCO — Google Inc. (Nasdaq: GOOG) plans to hire more than 6,200 workers this year in the biggest expansion yet by the Internet’s most profitable company.

Google’s push to further expand a work force that grew by 23 percent last year may not be as well received on Wall Street, where the Internet search leader’s spending has annoyed some investors who would prefer a more frugal approach in hopes of fatter returns.

[Google operates two outputs in North Carolina, a huge data center in Lenoir and a software development office in Chapel Hill.}

Google executives have consistently brushed aside those concerns, saying that the company needs to aggressively recruit the smartest computer engineers and most persuasive sales representatives to maintain its lead in online search and advertising, as well as to diversify into other services in computing, telecommunications and the media.

The company outlined its hiring plans Tuesday with The Associated Press without providing many specifics beyond its pledge to hire more people than it did in 2007 when it added 6,131 workers. Google hired nearly 4,600 people last year to end 2010 with 24,400 employees. Based on its hiring commitment, Google’s work force will increase by at least 25 percent this year.

Analysts polled by FactSet expect Google’s net revenue to increase 22 percent this year.

Google wouldn’t say how many of the new jobs will be based in the United States, where most of its current workers are located. In a speech Tuesday, Schmidt said Google will hire more than 1,000 workers in Europe this year. All told, Google has more than 60 offices in 30 countries.

“At this stage, the number of opportunities just vastly exceed the number of people we have at the company,” said Alan Eustace, Google’s senior vice president of engineering and research.

Even if it surpasses 31,000 employees this year, Google will still have far fewer people than Microsoft Corp., probably its fiercest rival. Microsoft employed about 88,400 people through September, the most recent head count available.

Managing a company with the population of a small city will pose another challenge for Google co-founder Larry Page as he prepares to take over as the company’s CEO April 4 in a shake-up that will reassign Schmidt to executive chairman. In that role, Schmidt will focus on meeting with government officials, business partners and potential takeover targets while Page runs the company.

(Read about the changes here,)

Page, 37, served as CEO in Google’s early days when the company was far smaller. Google had fewer than 300 employees when Schmidt replaced Page as CEO a decade ago.

Google has become a coveted place to work, largely because Page and fellow co-founder Sergey Brin have always insisted on making the company’s offices seem like a home away from home in an effort to make people more productive. All meals, snacks and drinks are free at Google, and employees can commute on free shuttles equipped with Internet access to San Francisco and other cities located within a 50-mile (80-kilometer) radius of the company’s Mountain View, California, headquarters.

The sprawling headquarters, dubbed the “Googleplex,” is a testament to the company’s explosive growth and its ambitions to become far larger.

Google owns or leases about 4.2 million square feet (about 0.4 million square meters) scattered across more than 60 buildings in Mountain View and hopes to build another corporate campus on a nearby NASA complex in Silicon Valley. It also signaled plans to expand in New York last year when it paid about $2 billion to buy a 15-story office spanning about 2.9 million square feet (0.27 million square meters) — more space than the Empire State building. About 2,000 Google employees currently work in that New York office.

Trying to get a job at Google is akin to trying to get into Stanford University, where Page and Brin started working on their search engine as graduate students. The company receives more than 1 million applications a year and identifies the top candidates through a rigorous screening process that analyzes SAT scores, grade point averages and their performance on tests with mind-questions such as: “How many different ways can you color an icosahedron with one of three colors on each face?”

The people who make it through Google’s intellectual gauntlet will likely be under intense pressure if they get hired. Management is pushing aggressively for more innovation so that the Internet giant can compete against emerging threats from smaller companies such as Facebook and Twitter.

“The opportunities are so big this year that for us to maximize them we are going to have to work quicker and we are going to have to make decisions faster,” Eustace said.

As its Internet social network grows, Facebook has become more successful at luring away Google’s workers. About 200 of Facebook’s roughly 2,000 employees formerly worked at Google. The defections haven’t left a big dent, given that the company hired an average of nearly 200 workers every two weeks last year.

But the recent raids by Facebook and other promising startups got Google’s attention. In an effort to retain its current employees, the company this year gave its entire work force a raise of 10 percent. That move alone could increase Google’s operating expenses by about $500 million this year, based on analyst estimates. Virtually all employees also receive stock options, a benefit that turned most of the company’s early hires into multimillionaires.

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