Apple was blocking some app updates because they said they worked with a rival to the Apple Watch

Apple blocked updates to apps that said they are compatible with the Pebble, one of the biggest rivals to the Apple Watch, for a few days this week.

According to sources familiar with the issue, Apple wouldn't publish updates to apps if they said they were compatible with Pebble. It all started this week, and there was no issue before. In fact, Pebble's own app was updated just last week. The Apple Watch launched Friday.

An Apple spokesperson told Business Insider that apps won't be denied on the grounds that they work with Pebble .

Apple was denying the apps under rule 3.1 of the App Store developer rules, which says apps cannot work with rival mobile platforms, according to sources.

Here's what rule 3.1 says:

Apps or metadata that mentions the name of any other mobile platform will be rejected.

Technically, Apple didn't have a rival platform to Pebble until this week, which could explain why Apple's reviewers started blocking updates to Pebble-compatible apps.

A developer for the app SeaNav came forward this week and said Apple denied his app update on the grounds that it worked with Pebble. The update to Seanav is now live in the App Store.

Pebble is launching its new smartwatch, the Pebble Time, in a few weeks.