The sale of extra tickets is open only to Comic-Con members as of Feb. 29, and people who have already purchased four-day or Saturday passes are not eligible, according to organizers. Those who will be allowed to purchase badges have been informed by e-mail.
The initial ticket sale, on March 3, resulted in a sellout in a little over 80 minutes.
An undisclosed number of those passes became available due to cancellations or other reasons, the organizers said.
The 2012 Comic-Con International, the largest annual event at the Convention Center, will run from July 11-15.