Search giant Google will shed 200 jobs in sales and marketing, half of which are based in US – the biggest round of layoffs in the company’s history.

According to a report from AdAge.com, the move is the latest in a string of staff cuts since the beginning of the year as the company retrenches in the face of an ad recession that is affecting its core search-advertising business.

Google laid off 100 recruiters in January, and cut another 40 staffers last month with the closing of its less than successful radio-ad-sales initiative. The company has doubled staff in the past two years, growing from 10,674 at the end of 2006 to 22,222 at the end 2008.

“When companies grow that quickly, it’s almost impossible to get everything right and we certainly didn’t,” Google’s senior vice president of sales and business development, Omid Kordestani, explains in a blog post.

Google said the affected employees would be offered the opportunity to find other jobs at the company or to receive outplacement support and a severance package.

The cutting of the jobs globally comes on the heels of the departure of former Google US president, Tim Armstrong, who has since been named CEO of Time Warner’s AOL. His replacement is Dennis Woodside, Google’s vice president of operations for the UK, Ireland and Benelux.