Twitter is to test doubling the characters limit in tweets to 280, double the existing cap, in most languages around the world.

The test will involve a random sample of users.

The move was inspired by how people use Twitter when writing in Chinese, Japanese and Korean.

Characters in those languages can often express more than Roman characters can, meaning those users already, in effect, have a higher limit.

They also use Twitter more often.

The San Francisco-based company has stood by its short messages as a defining characteristic even as users found ways around the limit, such as posting photos of text.

In a blog post, Twitter said its emphasis on brevity would never change but that it had been wondering whether people could express themselves easily enough, hurting the service's popularity.

"Trying to cram your thoughts into a Tweet - we've all been there, and it's a pain," Twitter project manager Aliza Rosen and senior software engineer Ikuhiro Ihara said in the post.

The employees acknowledged some users may have an "emotional attachment" to the current limit.

Though Twitter is ubiquitous in media because of frequent use by US President Donald Trump and many celebrities, the company has struggled financially.

For the second quarter, it reported a loss of $116 million and zero growth in the number of users, at 328 million people.

Facebook Inc has 2 billion users.