Google on Wednesday announced that 500 million devices running on its Android operating system have been activated so far.

"Today is a big day for Android... 500 million devices activated globally, over 1.3 million added every single day," Hugo Bara, Google Android's director of product management, said in a Google+ post.

In June, Google said 400 million Android devices had been activated and the rate was 1 million per day.

Google announced the milestone just before Apple unveiled iPhone 5. The latest smartphone from Apple features a bigger screen and support for LTE network, both of which have been available on smartphones using Android system for more than a year.

According to latest data from research firm IDC, there were four Android phones for every iPhone shipped during the second quarter of this year. It is up from a ratio of 2.5 to 1 during the same period last year.