An Australian lawyer representing Julian Assange has been named on a border control list, a British newspaper reports.
Human rights legal specialist Jennifer Robinson, who is part of the WikiLeaks founder's team, said she was stopped as she attempted to board a flight to Australia in April.
"Why would I need clearance to travel to my own country? So far, I have not received a proper explanation," 31-year-old Ms Robinson told The Mail on Sunday.
Virgin Atlantic crew at London's Heathrow airport told Ms Robinson she must have "done something controversial" to be on the "inhibited person list", which WikiLeaks supporters say is a secret database operated by British and US authorities.
Both governments deny the practice.
Ms Robinson was eventually issued with a boarding pass and allowed to catch her flight.
Meanwhile Mr Assange, who remains holed up in London's Ecuadorian embassy in a bid to avoid extradition to Sweden for an investigation over sex assault allegations, has sent a message to his faithful supporters.
During an interview filmed inside the embassy Mr Assange said people staging a 24/7 vigil outside should leave for their own welfare.
Some supporters have spent more than two weeks camped outside the Knightsbridge address amid fears Mr Assange will be forcibly arrested by British authorities.
In the interview Mr Assange says he feels safe and that his supporters should care for their own health.