increasing the authorized stock of a corporation

In Nevada, what is required to increase the authorized share capital of a company, is it only approved at an AGM or can the directors increase the share capitalization at a board meeting.

Thank you

The following link will take you to the Nevada statute requiring a resolution of the board of directors for a change in number of shares:
http://www.leg.state.nv.us/NRS/NRS-078.html#NRS078Sec207

The following link is the Nevada law giving you the procedures for amending the articles, etc. re the change in number of shares:
http://www.leg.state.nv.us/NRS/NRS-078.html#NRS078Sec209