WikiLeaks founder Julian Assange has been denied bail in the UK, days after he avoided being extradited to the United States .

District Judge Vanessa Baraitser refused bail at Westminster Magistrates Court in London as the US government appeals against a decision to block his extradition.

In a court hearing on Monday, Judge Baraitser said that, due to his real risk of suicide, the 49-year-old Australian should not be extradited by reason of mental health.

But she rejected his legal teams arguments that the prosecution was politically motivated or a threat to freedom of speech.

Assange is wanted to face an 18-count indictment, alleging a plot to hack computers and a conspiracy to obtain and disclose national defence information.