The Sydney Morning Herald quoted the AFP that Iceland criticized the US following its probe of the Twitter account of parliamentarian and former WikiLeaks supporter, Birgitta Jónsdóttir.
Jónsdóttir contacted the justice minister in Iceland and wanted to meet with the American envoy to make a complaint.
Foreign Minister Oessur Skarphedinsson said he would discuss the matter with the US ambassador in Reykjavik.
Skarphedinsson said in a RUV radio interview, "According to the documents that I have seen, an Icelandic parliamentarian is being investigated in a criminal case in the United States for no reason at all."
"It is intolerable that an elected representative is being treated like that," he added.
Jónsdóttir said on Saturday, "(Twitter) actually fought this on behalf of their customers because this sort of information should really not be handed over, in particular because there is no criminal case here."
She further said, "I am speaking to US lawyers...because I want to try to stop that Twitter needs to hand over this information, on the principle."
Outraged by the subpoena, WikiLeaks founder Julian Assange accused the US government of "intruding in to the private lives" of WikiLeaks supporters.
However, legal experts say that this is a normal procedure in criminal investigations. The same subpoenas are issued for phone records and bank statements.
CNN legal analyst Jeffrey Toobin said that this is just a basic law-enforcement procedure.
Toobin also said, "Social media is at its core about putting information out in the social world. If you don't want people to know what you are thinking, don't tweet it."
Aside from Jónsdóttir, other WikilLeaks activists whose Twitter accounts are being investigated are Jacob Appelbaum, Rop Gonggrijp, and Julian Assange.
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