US courts have issued a subpoena to Twitter, demanding it hand over the details of people connected to WikiLeaks, court documents have revealed.
The US government is contacting Internet companies and social networking websites for information on people related to the whistle-blowing website as part on an ongoing criminal investigation, The Independent reports.
Pressure is also mounting on Facebook and Google to reveal whether the US government has forced them to submit similar information.
The government is building a case against WikiLeaks founder Julian Assange and former US military official Bradley Manning. The latter is suspected of leaking 250,000 US diplomatic cables, amongst other information.
US law officials are also planning to charge other main contributors to the site in the process, and in their fervour have demanded Twitter hand over the details of Icelandic MP Birgitta Jónsdóttir.
In response, the Icelandic government has summoned the US ambassador to explain his country's actions.