PRINEVILLE, Ore. -- Just days after reaching the milestone of a half-billion users, Facebook announced Friday that it will double the size of its first wholly-owned data center, now under construction in Prineville.

The expansion will add another 160,000-square-foot shell to the 147,000-square-foot facility now being built, the company said.

"As business needs dictate, the shell will be built out to accommodate more servers," the statement said.

"We are making excellent progress on the first phase of our Prineville Data Center and we are hoping to finish construction of that phase in the first quarter of 2011," said Tom Furlong, director of site operations for Facebook.

"To meet the needs of our growing business, we have decided to go ahead with the second phase of the project, which was an option we put in place when we broke ground earlier this year," Furlong said. "The second phase should be finished by early 2012."

Facebook, the world's largest online social network, recently announced that it reached the milestone of 500 million users.

Facebook announced the project in January 2010 and broke ground on the facility shortly afterwards.

"We couldn't be happier with our choice of location. The Prineville and Central Oregon communities have been excellent partners," said Ken Patchett, Facebook's data center manager.

The expansion will create additional construction employment, said Patchett. During construction, there are between 150 to 200 workers on site on any given day. The Prineville Data Center will create 35 long-term jobs. For information about employment opportunities, go to Facebook.com/careers.