Assange facing a long-term stay in Ecuadorean embassy

A member of Anonymous in a Guy Fawkes mask outside the embassy (Getty Images)

Julian Assange will never be allowed free passage out of Britain, the Government said last night, raising the prospect of the fugitive WikiLeaks founder's effective imprisonment inside the Ecuadorean embassy for months or even years.

Ecuador threw down the gauntlet to the UK, Sweden and the US by granting asylum to Mr Assange, who has been in its cramped embassy in West London for two months, avoiding extradition to Sweden to face allegations of rape.

Following a dramatic day which saw protests, arrests and an increasingly ugly diplomatic fallout between the UK and Ecuador, the South American country's foreign minister said it was granting asylum to Mr Assange, 41, because of "serious indications" that the US could threaten the Australian's "security, integrity and even his life".

Washington is furious that Mr Assange published thousands of confidential US diplomatic cables online and some Republican politicians have called for the death penalty if he ever faces espionage charges in America. Britain insists that nothing has changed now that he has been granted asylum. He can only leave the embassy and travel to the Ecuadorean capital, Quito, if Britain agrees to allow him safe passage to an airport. Quito has warned that any attempt to enter the embassy and seize Mr Assange would constitute an assault on Ecuador's sovereignty and would be tantamount to an "invasion".

Last night, in an announcement that sparked rumours that Mr Assange might be willing to court arrest, WikiLeaks said its founder would give a statement at 2pm on Sunday "outside the Ecuadorean embassy". The brief statement on Twitter was surprising as it has been assumed diplomatic immunity ends at the front door. The mansion block which holds the embassy is also home to its Colombian counterpart and a host of luxury flats, so police could arrest Mr Assange as soon as he steps into the lobby.

The deepening acrimony is poisoning British relations with other nations in South America. Argentina, Bolivia and Venezuela – all hostile to the UK – already back Ecuador, and the UK Government anxiously awaits Brazil's reaction.

Whitehall sources admitted that an apparent threat – delivered by a diplomat in Quito – to raid the London embassy had inflamed the situation.