Twitter has admitted that its iPhone app uploads the entire contents of a user's address book for up to 18 months.
The LA Times reports that if you use the Find Friends feature in the Twitter app personal data such as names, email addresses and phone numbers of your contacts is uploaded to Twitter's servers.
While you will see a message telling you that the data is being scanned - ostensibly to make it easier to connect to friends and contacts who are already on Twitter but that you are not yet following - it doesn't explicitly state that the data is being uploaded and stored.
A Twitter spokeswoman told the LA Times that the company planned to make it clearer to users of the iPhone app how their data was being used in future.
"In our next app updates, which are coming soon, we are updating the language associated with Find Friends to be more explicit," said the spokeswoman.
If you have used the Find Friends feature you can follow this link to remove your data from the company's servers, the spokeswoman added.
The admission comes after the developers of two iOS apps - Path and Hipster - came under fire for uploading data from users' address books without making this fact clear or explicitly asking for permission to do so.