Facebook says half of its employees may be far away

Geographically, Facebook will start in areas near its existing offices, including Portland, San Diego, Philadelphia and Pittsburgh, Zuckerberg said. Facebook's second priority, he said, will be to set up updated employee "centers", which currently have less business, first in Atlanta, Dallas and Denver.

Zuckerberg admits that wages in these areas are likely to be lower than those in the San Francisco Bay area.

Facebook is also considering providing permanent telecommuting support for existing employees. Zuckerberg said that as the company considers reopening offices, he expects only about 25% of Facebook employees to return to their desks at first.

Those who choose to continue working remotely will be required to report their location to the company, Zuckerberg said. The requirement will come into effect on January 1 next year.

"We will set January 1 as a date," Zuckerberg said. "you either need to move back to the same place or tell us where you are now, and we will adjust your salary according to where you worked at the time."