As it typically happens after a big announcement, Apple on Monday said that sales of its new iPhones are on pace to beat the 10 million units the previous versions logged in their first weekend last year. However, the company did not disclose the specific number of advance orders it received. It said it was working to catch up to demand for the iPhone 6S Plus, the larger of the two new phones, which exceeded its forecasts for the preorder period.

"Customer response to iPhone 6S and iPhone 6S Plus has been extremely positive, and preorders this weekend were very strong around the world," Apple's Trudy Muller said in a statement. Apple began taking preorders on Saturday for the iPhone 6S and iPhone 6S Plus, which will begin shipping Sept. 25.

Apple's announcement comes at a period in which many analysts are wondering whether Apple could keep offering products that will increasingly sell well.

The iPhone 6S and 6S Plus feature improved cameras, processors and 3D touch, a display technology that responds according to how hard users press their screens.