SAN FRANCISCO - Twitter on Wednesday launched a system for emergency alerts which can help spread critical information when other lines of communication are down.

The popular messaging service said its Twitter Alerts could be useful in natural disasters or other emergencies when traditional channels may be overloaded or unavailable.

"We know from our users how important it is to be able to receive reliable information during these times," Twitter product manager Gaby Pena said in a blog post.

"Twitter Alerts is a new way to get accurate and important information when you need it most."

Last year, Twitter announced a service called Lifeline to help Japanese users find emergency accounts during crises "and since then, we've been working on a related feature for people around the world," Pena said.

"Today, we're launching Twitter Alerts, a new feature that brings us one step closer to helping users get important and accurate information from credible organizations during emergencies, natural disasters or moments when other communications services aren't accessible."

Users who sign up to receive an account's Twitter Alerts will receive a notification directly to their phone for tweets marked as alerts from certain senders.

A number of organizations in the United States, Japan and South Korea have been authorized to send such alerts, and Twitter will expand this to "public institutions and NGOs around the world."

Some of those able to send alerts include the American Red Cross, Federal Emergency Management Agency, World Health Organization, and government and non-government agencies in Japan and South Korea.

Twitter's Bridget Coyne said the messaging platform became a vital information source following the Japan tsunami, and in the United States for Superstorm Sandy and the Boston bomb attacks.

She said those likely to use the alerts include law enforcement and public safety agencies, emergency management agencies, local governments and private organizations involved in disaster relief.