Research by the Pew Institute found that 11% of US web users are 'tweeting' as of December 2008, a two percentage point rise from a month earlier.
Amanda Lenhart, senior research specialist at Pew, said: "The use of Twitter is highly intertwined with the use of other social media. Both blogging and social network use increase the likelihood that an individual also uses Twitter."
Pew found that 23% of social network users also use Twitter while 4% of those who do not log on to social networking sites do.
More than a quarter of bloggers are also using Twitter compared to just 10% who don't keep a blog.
One in five 18-34 year old are using the service, while usage drops off progressively after that age, with 10% of 35-44 year-olds tweeting, and 5% or less of the 44+ age group.
Twitter last week secured $35m in new capital in a funding round led by Benchmark Capital and Institutional Venture Partners, with Benchmark partner Peter Fenton joined the Twitter board. Two previous rounds raised a total of $20m.
On Twitter's blog, co-founder Biz Stone, wrote: "Our strong growth attracted interest and we decided to accept a unique opportunity to make Twitter even stronger with a very attractive offer.
"Last night, we closed on funding with our friends Peter Fenton from Benchmark and Todd Chaffee from Institutional Venture Partners. When Ev and I visited IVP we were very impressed and Benchmark's approach regarding teamwork was equally inspiring — every partner is invested in each others success. Peter will be joining our board of directors which means we gain his experience and savvy in addition to that of all his partners."
Stone said that Twitter was now well positioned to support the accelerating growth of the service and begin building revenue-generating products.
"Throughout this year and beyond, our small team will grow much bigger to meet the challenges and opportunities ahead.
"Twitter is making a real impact around the world as people, companies, and organizations everywhere discover a powerful new way to communicate and find out what's happening—right now. With these new partnerships and this new funding, we are in a position to move more confidently toward our vision for a robust and successful Twitter, Inc."
The company has yet to secure a realistic revenue stream; however, it has been openly discussing the idea of charging businesses and brands to use the service.
Also last week it organised a global fundraising push for Charity: Water, called Twestival, with events coordinated through Twitter around the globe. The London Twestival drew more than 700 users with spillover events organised to compensate for over capacity.
A separate study has shown that the worsening economy has raised the profile of professional social networking site LinkedIn.
According to January data from comScore, visitors to LinkedIn in the US rose 22% from December, up to 7.7m.
Total minutes spent on the site have doubled in the same time frame, up to 96.8m in January from 47.6m in December.