Downing Street says an EU demand for an extra £1.7bn budget contribution ($2.7bn) from the UK is 'not acceptable'.
Brussels has made new calculations on what member states should contribute and the UK is being asked for more because of its recent strong economic performance.
The additional funds are due on the 1st December.
The UK says it will work with other countries - like Holland - which are also being asked for more money at short notice.
Some nations like France and Germany are set for a rebate.
Rob Oxley from Business for Britain says the demand must be challenged.
IN: "Well come….
OUT: ...more money."
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