Twitter announced Tuesday a test project allowing tweets to be expanded to 280 characters -- double the existing limit -- in the latest effort to boost flagging growth at the social network.

San Francisco-based Twitter said the new system, a major shift for the messaging platform known for its 140-character tweets, aims to address "a major cause of frustration" for many users.

A "small group" of users will see the new limits before Twitter decides on rolling out the changes more broadly