The final bill could be much more as the 41-year-old continues to defy extradition to Sweden where he is suspected of sexually assaulting two women.
Scotland Yard confirmed it costs 11,000 pounds every day to ensure that the Australian does not flee his bolthole at the Ecuadorean Embassy, the Daily Mail reported.
The police bill for staking out the embassy where Assange is holed up has already reached more than 1 million pounds.
Officers have been watching the property in Knightsbridge, West London, since Assange breached his bail and claimed asylum in June. They have been told to arrest him if he puts "one toe" outside.
Ecuador granted political asylum to Assange in August after he took refuge in the country's embassy in London.
Ecuadorean foreign minister Ricardo Pinto has warned Assange he could be in the embassy for a decade if he is not allowed to leave Britain.
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Critics have called on the Metropolitan Police to end the costly stakeout.
London Mayor Boris Johnson confirmed the policing bill between June 20 and September 10 was 905,000 pounds.
If the costs continued at the average of 11,000 pounds a day the total would now be over 1.1 million pounds.
Last week, Foreign Secretary William Hague admitted there is "no sign of any breakthrough" after meeting his Ecuadorean counterpart Ricardo Pinto at the United Nations in New York.
The comments came after the hacking activist accused the US of persecuting WikiLeaks and torturing Bradley Manning, the soldier accused of leaking classified documents.
At least four Metropolitan officers guard the embassy, on the second floor of a block of flats behind Harrods in Knightsbridge, West London, around the clock.
They have set up a 250,000 pounds mobile command station on the doorstep of the building and occupy positions outside and in surrounding properties.
Officers from every London borough, specialist police units and undercover squads have been brought in to join the open-ended stake out.
Critics called on the police to end the stand-off but sources said the force cannot step back from its responsibilities to arrest Assange for breaching his bail.
Australian hacker-turned-activist is trying to avoid extradition from Britain to Sweden over allegations of rape and sexual assault in August 2010.
Assange fears that he may be sent to the US, if extradited to Sweden, and face charges punishable by death for publishing some 250,000 leaked American diplomatic cables.