Apple Inc said it is experiencing some issues with its App Store, Apple Music, iTunes Store and some other services.
The company did not provide details but said only some users were affected.
Checks by Reuters on several Apple sites in Asia, Europe and North and South America all showed issues with the services.
The problems appear to have started just before 10 a.m. ET, according to a timeline on Apple's U.S. support page.
Apple Insider, a tech news blog, said the disruption was likely caused by excess traffic associated with the announcement of MTV's 2015 Video Music Awards nominees, made exclusively on Apple's Beats 1 music service.
"We are investigating and will update the status as more information becomes available," Apple said on the support site.
Apple, which is scheduled to report its third-quarter results later on Tuesday, was not immediately available for comment.