SAN JOSE, Calif. — Extending a surge that began last year, Google Inc. says 2011 will be its largest hiring year ever, plans that would mean the Internet giant will add more than 6,000 new workers over the balance of this year.

With the hiring plans, Google will have more than 30,000 employees by the start of 2012, a workforce still significantly smaller than Silicon Valley giants like Intel Corp., Cisco Systems Inc. and Hewlett-Packard Co., but more than double the size of rivals like Yahoo Inc., and more than six times the size of the company that has become its most formidable competitor – Facebook Inc.

The company is rapidly increasing the number of engineers working on initiatives such as its Android operating system for smart phones and tablets, its maps and location-based services that could deliver advertising to users based on their location, and in its Chrome browser and operating system areas.