Twitter has announced that it will start filtering messages and preventing them from being seen in some locations. In a blog post the firm acknowledged that some countries have different ideas about what “freedom of expression” means.

“As we continue to grow internationally, we will enter countries that have different ideas about the contours of freedom of expression. Some differ so much from our ideas that we will not be able to exist there. Others are similar but, for historical or cultural reasons, restrict certain types of content, such as France or Germany, which ban pro-Nazi content,” it said.

“Until now, the only way we could take account of those countries’ limits was to remove content globally. Starting today, we give ourselves the ability to reactively withhold content from users in a specific country – while keeping it available in the rest of the world. We have also built in a way to communicate transparently to users when content is withheld, and why.”

The firm said that it has not used the feature yet, and that it will make it clear to users when their tweet has not got through. It has created a page with an organisation called Chilling Effects ( http://chillingeffects.org/twitter ) that users can turn to to find out if and when content has been withheld.

“One of our core values as a company is to defend and respect each user’s voice. We try to keep content up wherever and whenever we can, and we will be transparent with users when we can’t. The Tweets must continue to flow,” it added.