Boris Johnson should block attempts to extradite Julian Assange to the US, say two Australian MPs who have flown to the UK to visit the WikiLeaks founder.

Andrew Wilkie, an independent federal MP, said the extradition of Assange, who has been charged by the US with conspiring to hack into a secret Pentagon computer network, would set a dangerous precedent.

“This will establish a precedent that if you are a journalist who does anything that offends any government in the world then you face the very real prospect of being extradited to that country,” he said. “This is a political case and what is at stake is not just the life of Julian Assange. It is about the future of journalism.”

Wilkie was joined in London by the co-chair of the Bring Julian Assange Home parliamentary group, the Liberal National MP George Christensen, who said he and Wilkie had come to speak directly with the WikiLeaks founder. He said he was joining forces with those on the left even though he was a conservative.