The move was followed by a summons for the Ecuadorean ambassador to a meeting at the Foreign Office to discuss the case, which has been deadlocked for years.
The meeting was held at the Foreign Office, where a spokesman said: “The head of the Diplomatic Service, Simon McDonald, summoned the Ecuadorean ambassador today to register once again our deep frustration at the protracted delay.
“The UK has been absolutely clear since June 2012 that we have a legal obligation to extradite Assange to Sweden. That obligation remains today.”
Assange has been granted political asylum by the Ecuadorean government as part of his attempt to avoid extradition to Sweden over sex attack allegations, fearing he will be taken to the US for questioning over the activities of WikiLeaks.
Police pull 24-hour guard of Julian Assange's London embassy hide out: Police in London have removed their aro... http://t.co/p97CTGsevS— Geek me _ (@Geekme_) October 12, 2015
Officers have been stationed outside the embassy around the clock since 2012 at an estimated cost of more than £12m.
The Metropolitan Police Service said it still intended to arrest Assange but added: “Like all public services, Metropolitan Police Service resources are finite.
"With so many different criminal, and other, threats to the city it protects, the current deployment of officers is no longer believed proportionate.”
Assange was arrested on a European arrest warrant in December 2010 and ordered to face extradition to answer sex charges, which he denies.
He faces immediate arrest should he emerge.
Last month, prosecutors dropped cases of alleged sexual misconduct against the 44-year-old but they say they want to question him about accusations of rape made after his visit to the country five years ago.