The screenshot also captured two other messages, subsequently deleted, on the Fox News Politics feed, one taking credit for the hack and another directed at Anonymous, the hacking collective that has led a highly successful hacking campaign. That tweet also referred to "antisec," short for "Anti-Security," an ongoing hacking operation conducted by Anonymous that has antagonized companies and governments by defacing websites and, in some cases, stealing sensitive data.

The first in the series of strange tweets still visible on the account said that the account owners had regained full access to e-mail and the Twitter feed, in an attempt to allay suspicion about the earlier, now deleted, messages.

Twitter typically moves quickly to delete tweets that come from hacked accounts and has overall stepped up its security. But like many web-based services, Twitter uses logins and passwords to allow access to accounts, which hackers have proved adept at stealing through social engineering techniques and malware on computer such as keyloggers.

Officials at Twitter, which is based in San Francisco, California, could not be immediately reached.