Labour leader Jeremy Corbyn said that Assange had revealed "evidence of atrocities in Iraq and Afghanistan" and
his extradition "should be opposed by the British government".
Press freedom organisation Reporters Without Borders said that the UK should resist extradition, because it would "set a dangerous precedent for journalists, whistleblowers, and other journalistic sources that the US may wish to pursue in the future".
Australia's Foreign Minister Marise Payne said he would continue to receive "the usual consular support" and that consular officers will try to visit him.
And actress Pamela Anderson, who has visited the embassy to support Assange, said
the arrest was a "vile injustice".
Pamela Anderson condemns Assange arrest and says Britain is 'America's b**ch' and 'needed a diversion from your idiotic Brexit bulls**t'