Wikileaks' Australian founder Julian Assange, who enraged Washington by publishing thousands of secret US diplomatic cables, has been given a peace award for "exceptional courage in pursuit of human rights".

Assange was awarded the Sydney Peace Foundation's gold medal on Tuesday at the Frontline Club in London, only the fourth such award to be handed out in its 14-year history. The not-for-profit organisation is associated with the University of Sydney and supported by the City of Sydney.

Assange, who is fighting extradition from Britain to Sweden over alleged sex crimes, was praised for "challenging centuries-old practices of government secrecy and by championing people's right to know".

"We think the struggle for peace with justice inevitably involves conflict, inevitably involves controversy," the foundation's director, Professor Stuart Rees, said.

"We think that you and WikiLeaks have brought about what we think is a watershed in journalism and in freedom of information and potentially in politics."

Rees criticised the Australian government, saying it must stop shoring up Washington's efforts to "behave like a totalitarian state", and said the foundation was "appalled by the violent behaviour by major politicians in the United States".

WikiLeaks caused a media and diplomatic uproar late last year when it began to publish its cache of more than 250,000 US diplomatic cables, revealing secrets such as that Saudi leaders had urged US military action against Iran. Some US politicians said WikiLeaks should be defined as an international terrorist organisation.

Assange himself claimed publication of the cables helped shape uprisings in north Africa and the Middle East and said WikiLeaks was on the side of justice.