WikiLeaks founder Julian Assange has allegedly threatened to sue The Guardian for leaking material from the whistle-blowing site without his express permission.

Vanity Fair has revealed that, in an ironic episode, Assange stormed into the office of Guardian editor Alan Rusbridger last November, threatening to take the paper to court for publishing information that had been provided by a disgruntled volunteer without his authorisation.

Assange also terminated an agreement with the publication that allowed them to publish leaked sources from the site. The deal had specified that The Guardian could only write stories about the leaks with his personal agreement.

The WikiLeaks founder has been embroiled in a number of scandals over the last few months, with the most serious being his arrest and subsequent bail in the UK over sex crime allegations in Sweden, where he faces extradition.

WikiLeaks has also suffered recent setbacks after a number of high profile internal defections the freezing of its assets by financial organisations.