WikiLeaks founder Juilan Assange has emerged for a rare public address from the balcony of the Ecuadorean Embassy in London where he has spent six months in refuge.

Addressing supporters on a cold and wet English evening, the 41-year-old Australian looked healthy despite half a year spent trapped inside the small apartment he shares with Ecuador's diplomatic staff.

Assange, who is being investigated by U.S. officials over his spectacular leaks of classified documents, is also wanted over allegations of sexual assault stemming from a trip to Sweden in mid-2010.

Although diplomatic immunity means that authorities can't reach him at the embassy, British officials have vowed to arrest him if he sets foot outside. Assange gave no hint on Thursday that the standoff would end.