U.S. officials have issued a subpoena to demand details about WikiLeaks' Twitter account, the group announced Saturday, adding that it suspected other American Internet companies were also being ordered to hand over information about its activities.

In a statement, WikiLeaks said U.S. investigators had gone to the San Francisco-based Twitter Inc. to demand the private messages, contact information and other personal details of WikiLeaks founder Julian Assange and other supporters, including the U.S. Army intelligence analyst suspected of handing classified information to the site and a high-profile Icelandic parliamentarian, The Associated Press reported.

WikiLeaks blasted the court order, saying it amounted to harassment. WikiLeaks denies U.S. charges that its postings could put lives at risk, saying that Washington merely is acting out of embarrassment over the revelations contained in the cables.