Madrid — Catalan independence activists looking for information on how to take part in the next protest against Spain can rely on a handy, two-day old app for details on when and where to go. The only catch: the app does not work on iPhones.

That has prompted iPhone-wielding campaigners to ask why they are being left out of the loop. Democratic Tsunami, the group organising the protests, and which created the app, says it is simply about security.

The reason is that Apple’s App Store has restrictive policies on such applications and it has already “censored” similar mechanisms for demonstrations in Hong Kong, Democratic Tsunami said in a statement published on Wednesday on social media and instant messaging devices.

The app was released on Tuesday, the day after a Spanish Supreme Court ruling sentenced nine separatist leaders to a combined 100 years in prison, sparking the street protests that have led to three days of rioting on the streets of Barcelona.

Spain’s interior minister Fernando Grande-Marlaska has said his department would investigate who is behind Tsunami Democratic, which has mobilised big demonstrations, including a major protest at Barcelona airport. Police have made 96 arrests.

Android users are made to download the app through a link, without having to go to the Google app store. But downloading the app is only the first step. Once a user has it, a QR code is required to access it and the only way to get the code is from somebody who already has it — a strategy the activists say will help limit who has access to the information.

The app was made public on Tuesday and by Wednesday afternoon it had 150,000 downloads, according to the statement from Democratic Tsunami.

Apple’s press office in Madrid did not immediately respond to e-mails and phone calls seeking a company response.