WikiLeaks founder Julian Assange has waded into the row over American drone strikes, urging the leak of confidential government guidelines on drones during an interview with US talk show host Bill Maher.

Assange, speaking from the Ecuadorian embassy in London, where he has been holed up since June, attacked America's record on killing its own citizens, claiming "you can be killed by someone in the White House, the president on down, completely arbitrary reasons. You won't know you're on the kill list until you're dead."

The interview follows reports in America that the US government reserves the right to kill its citizens extrajudicially if it believes them to be an "imminent" threat to national security.

An NBC News report this week claimed that:

"A confidential Justice Department memo concludes that the U.S. government can order the killing of American citizens if they are believed to be “senior operational leaders” of al-Qaida or “an associated force” -- even if there is no intelligence indicating they are engaged in an active plot to attack the U.S."

Assange is wanted for questioning in Sweden over claims of sexual assault but is refusing to travel to Scandinavia amid fears he will be extradited to the United States over his controversial website.

The UK government has made it clear Assange, who denies the allegations, will be arrested if he steps outside of the embassy after jumping bail.

He went on to tell Maher the report showed why the world still need organisations such as WikiLeaks, saying: "When an executive can kill its own citizens arbitrarily at will, in secret, without any of the decision making becoming public, without even the rules of procedure, without even the laws behind it being public- that's why we need organisations like WikiLeaks."

The Australian brought up the case of Anwar al-Awlaki, who was killed in Yemen in 2011 in a targeted strike despite never having been charged with a crime in the United States. Al-Awlaki's son was also killed in a strike a fortnight later.

This week Julian Assange lost the backing of Jemima Khan, who told how her relationship with the Wikileaks founder moved from "admiration to demoralisation".

Khan, who was one of those who provided surety money for Assange when he was granted bail last year, spoke of her change of heart in an article for The New Statesman magazine.

In her article, Khan related how Assange reacted to a film, We Steal Secrets', about him that she was helping to produce.

"When I told Assange I was part of the 'We Steal Secrets' team, I suggested that he view it not in terms of being pro- or anti-him, but rather as a film that would be fair and would represent the truth . . . He replied: 'If it’s a fair film, it will be pro-Julian Assange.' Beware the celebrity who refers to himself in the third person . . ."