Measures to prevent WikiLeaks from publishing violate the site's right to freedom of expression, UN High Commissioner for Human Rights Navi Pillay said on Thursday.

She said that the pressure being exterted on private companies to stop services to the whistleblower site could be interpreted as an attempt to prevent WikiLeaks from publishing, thereby violating its right to freedom of expression:

"I am concerned about reports of pressure exerted on private companies including banks, credit card companies and Internet service providers to close down credit lines for donations to WikiLeaks, as well as to stop hosting the website," she told a news conference.

"If WikiLeaks has committed any recognisable illegal act then this should be handled through the legal system, and not through pressure and intimidation including on third parties."

The site and its founder Julian Assange have been under fire after it published thousands of classified war documents disparaging the US and other nations.

"If WikiLeaks has committed any recognisable illegal act, then this should be handled through the legal system, and not through pressure and intimidation including on third parties," Pillay said.

"The case raises complex human rights questions about balancing the freedom of information, the right of the people to know, and the need to protect national security or public order," she said.