According to an order issued by the District Court for Eastern District Virginia, Twitter has been directed to disclose the records of Julian Assange, Bradley Manning, Dutch hacker Rop Gongrjp and member of parliament in Iceland Birgitta Jonsdottir on the grounds that it believes they are relevant to an ongoing criminal investigation.
Jonsdottir, who had previously been a vocal supporter of Wikileaks, tweeted this morning: "The US is government is trying to criminalize whistleblowing and publication of whistleblowing material, puts journalists at risk in the future."
The information sought includes mailing addresses and billing information, connection records and session times, IP addresses used to access Twitter, e-mail accounts and the "means and source of payment".
Twitter has notified all users in question and said it would respond to the request within 10 days from the date of the notice, unless they decide to fight the order in court.
It is thought Google and Facebook have also been ordered to reveal details of user information.