The United Nations High Commissioner for Human Rights said she is concerned over reports of government pressure on Internet service providers and other companies to stop doing business with WikiLeaks.

Speaking on the eve of Friday's International Human Rights Day, she said the case raises complex questions about balancing freedom of information, the right of people to know, and the need to protect national security.

"I am concerned about the reports about pressure exerted on private companies, including banks, credit cards companies and Internet service providers to close down credit lines for donations to WikiLeaks as well as to stop hosting the website or its mirror sites," said Navi Pillay, UN High Commissioner for Human Rights, in a televised news conference in Geneva on Thursday.

"While it is unclear whether these individual measures taken by private actors directly infringe on states' human rights obligations to ensure respect of the right to freedom of expression, taken as a whole they could be interpreted as an attempt to censure the publication of information thus potentially violating WikiLeaks' right to freedom of expression," said Pillay. (See her comments in a YouTube video.)

Several of the Internet's biggest service providers, including Amazon Web Services and PayPal, have cut links with the controversial website since it began publishing U.S. State Department cables on Nov. 28.

The U.S. government has publically stayed away from pressuring U.S. companies to halt business with WikiLeaks, but on at least one occasion it did attempt to use its influence to do just that.

The U.S. Homeland Security and Governmental Affairs Committee was responsible for getting it kicked from Amazon's web hosting, according to claims made by U.S. Senator Joe Lieberman. Amazon later denied that government pressure had anything to do with the decision.

Most of the providers, including Amazon, have claimed they stopped business with WikiLeaks due to violations of their terms of service or because their infrastructure was being affected by denial of service attacks aimed at the website.

In recent days, denial of service attacks have been launched at other companies that have broken ties with WikiLeaks, including credit-card companies Visa and MasterCard.

"This is truly what media would call a cyber war. It's astonishing what is happening," said Pillay.

Martyn Williams covers Japan and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is martyn_williams@idg.com