Edward Snowden is a "hero" who has exposed "one of the most serious events of the decade – the creeping formulation of a mass surveillance state", Julian Assange said on Monday.

The WikiLeaks founder said the question of surveillance abuses by states and tech companies was "something that I and many other journalists and civil libertarians have been campaigning about for a long time. It is very pleasing to see such clear and concrete proof presented to the public."

Assange told Sky News that Snowden was "in a very, very serious position, because we can see the kind of rhetoric that occurred against me and Bradley Manning back in 2010, 2011, applied to Snowden".

Following the Cablegate exposures in 2010 there were calls from some US politicians for Assange to be tried for treason and even assassinated. Manning, who has admitted leaking classified US military secrets to WikiLeaks, is on trial facing 21 charges, including "aiding the enemy".

Assange has been confined for almost a year to the Ecuadorian embassy in London, having been granted asylum by the Latin American country in a bid to avoid extradition to Sweden to face sex assault and rape accusations, which he denies. The Australian fears answering the allegations in Sweden would make him vulnerable to onward extradition to the US to face potential charges relating to the WikiLeaks releases.

Assange had earlier told an Australian interviewer for ABC News that he had been in "indirect communication with [Snowden's] people", but declined to elaborate further.

He described Manning and Snowden as "very serious, earnest young men who really believe in something, and have shown great courage, and there is no doubt actually that history will look on them extremely favourably and perhaps, in a few years, will liberate them from their predicament."

Assange called on supportive countries to "line up" and offer support to Snowden. "It will be really telling to see which countries really protect human rights, the privacy of the public, asylum rights, or which countries are scared of the United States or are in bed with this surveillance complex."