WASHINGTON - Eleven per cent of Internet-connected US adults updated their status online using Twitter or another social network in December, nearly twice as many as in May, a survey released on Thursday said.

The survey by the Washington-based Pew Internet and American Life Project also found that the median age of a user of micro-blogging service Twitter is 31 years old as opposed to 27 for MySpace, 26 for Facebook and 40 for LinkedIn.

Pew said that 11 per cent of the 2,253 web-connected adults surveyed in December said they use Twitter or another service to share updates about themselves, up from nine per cent in November and six per cent in May.

Twitter allows users to send messages of 140 characters or less through a computer or mobile phone to other users. Social networks such as Facebook also feature a status update option.

Pew said that unsurprisingly, the use of Twitter and similar services drops off with age.

It said 19 per cent of online adults aged 18 to 24 years old said they have used Twitter or similar services.

Twenty per cent of those aged 25 to 34 said they have done so, 10 per cent of 35 to 44 year olds, five per cent of 45 to 54 year olds and just four per cent of 55 to 64 year olds.

Pew also said that 13 per cent of web-connected Americans surveyed said they have created a blog.

The Washington-based Pew Centre said the survey had a margin of error of plus or minus two to three percentage points. -- AFP