For more than a year, an @TheWhiteHouse account on Twitter's microblogging site was used to dutifully send out more than 1,500 alerts about speeches, press briefings and other Bush administration news. The Twitter account's claim that it was officially sanctioned by the White House appeared believable, if only because it was so earnest - and boring.

Then, when President Barack Obama was inaugurated on Tuesday, his picture appeared at the top of the Twitter page, and the updates continued. The number of "followers" who had signed up to get the updates quickly soared, from about 3,800 on Monday to nearly 16,000 as of Thursday.

But it turns out that the account was a fake.

Twitter officials Thursday changed the identifying information displayed on the @TheWhiteHouse page. Previously, the name of the account was listed as "The White House," and the biographical description read, "The head of the Executive Branch." Now the account name is "White House News," and the bio says in part that the account is "unaffiliated with the white house." In addition, Obama's photo has been removed and replaced by an icon. The person who set up the account isn't identified.

The changes - which were announced by Twitter CEO Evan Williams in a post on his Twitter page - are apparently within the company's right under its terms of service. But Twitter didn't close the account; instead, it simply changed the name and bio information to make it clear that the account isn't an official government one.

This isn't the first time that Twitter has changed inaccurate account information on pages, according to co-founder Biz Stone. "There have been other times when we've contacted account holders to let them know we have a policy against impersonation and had profile information changed accordingly," Stone wrote in an e-mail response to questions.

Asked whether Twitter searches out accounts that violate its terms of service, Stone wrote, "We proactively search for and remove spam and links to malware on our network, but we don't do the same for potential terms-of-service violations."

Twitter can shut down account for such violations if it finds them. But, Stone wrote, "shutting down accounts is not the only solution in all cases - for example, account holders may alter the profile so there is no longer any confusion."

Other accounts have purported to be posting updates from the US Senate , House of Representatives and Supreme Court .