Police have launched an investigation after thieves siphoned fuel from a pipeline running under Deputy Prime Minister Nick Clegg's official country residence.
Police said initial indications were that it had been "a well organised crime".
A gang drilled their way into the pipeline, which passes through Chevening House estate, shared by the Deputy Prime Minister and Foreign Secretary.
The fuel was funnelled along a 1,600 foot pipe to an area just outside the 3,500 acre estate near Sevenoaks, Kent, and pumped into huge plastic containers aboard lorries, according to The Sun.
About 30,000 litres of fuel a day was stolen over seven months, with a value of £8.3 million at pumps.
The theft was discovered on Wednesday after new security measures were introduced on Esso's South East Pipeline, the newspaper said.
The line, 120 miles long, carries fuel from Fawley Refinery in Hampshire to Purfleet Fuel Terminal and Gatwick.
A Kent Police spokesman said: "Kent Police was notified of some tampering to a fuel pipeline in the Sevenoaks area on August 6.
"Initial indications are that this was a well organised crime, employing highly specialist techniques to siphon fuel from pipelines which operate at very high pressure."
A spokesman for the Cabinet Office said: "We are aware of an ongoing police investigation. For more details talk to Kent Police."
Esso was not immediately available for comment.
An Esso spokesman said later: "We recently strengthened our pipeline security and monitoring procedures, and on Wednesday detected criminal damage at Chevening on the South East Pipeline, which transports fuel from the Fawley Refinery, Hampshire to Purfleet Fuel Terminal and Gatwick Airport.
"The section of pipeline was temporarily shut down to make repairs, which have now been completed.
"There has been no impact on supplies to customers.
"We strongly condemn the highly dangerous criminal action by those involved and are working closely with the police in their criminal investigations."
A spokeswoman for the National Crime Agency said: "We are aware there has been a report of some tampering to a fuel line in Kent and investigations are ongoing.
"If members of the public have any concerns about suspicious activity, such as excavation taking place at an unusual time or at an odd location, our advice is to contact the police, or contact Crimestoppers on 0800 555 111."