Twitter has launched Twitter Alerts in an attempt to help users get information from credible sources during emergencies such as natural disasters or when other communications services are down.

The company announced a similar feature - called Lifeline - last year to help Japanese users find emergency accounts during crises. The newer feature allows users to sign up to receive Twitter Alerts from a specified account.

They'll receive a notification directly to their phone whenever that account marks a Tweet as an alert. Users must go to an account's set-up page (example:[username]/alerts like to subscribe to notifications.

All notifications will arrive via SMS. They can also arrive via push notification if using Twitter for iPhone and Twitter for Android. The Alerts will also have an orange bell, so users can distinguish them from regular tweets.

Twitter said there were a number of organisations in the US, Japan and Korea now able to send Alerts, but the company said it would expand the service to include more public institutions and NGOs around the world.