David Cameron, pictured with other EU leaders on Friday, says the UK will not pay the bill by 1 December
Europe expects the UK to pay an extra £1.7bn towards the EU budget "and that's that", a vice president of the European Parliament has said.
Alexander Graf Lambsdorff, a German MEP, said the EU would be "exasperated" if the UK tried to avoid payment.
On Friday David Cameron said the EU had "another think coming" if it thought Britain would pay the bill by the 1 December deadline.
The EU demanded the extra amount because of growth in the UK economy.
Mr Lambsdorff told the Today programme on BBC Radio 4 that "everybody has to pay their dues".
He added: "If you have higher GDP growth than forecast, that also means logically that you have a higher contribution to the community's budget.
Alexander Graf Lambsdorff said the extra demand "should not have surprised anyone"
"That is a logical consequence. That is something that everybody has signed up for."
But Conservative MP Sir Bill Cash, speaking on the same programme, said it was "quite common" for member states to ignore EU demands.
"There may be consequences, but then they have to be weighed up," he said.
Sir Bill - who chairs the European Scrutiny Committee in the Commons - also said he would call in treasury ministers to his committee to see "how they intend to handle it from now on".
Former foreign secretary Sir Malcolm Rifkind said it was "ridiculous" to expect Britain to pay by 1 December.
He said there had been a "cock-up" by European statisticians and by British officials, who didn't initially realise that the demand was "political dynamite".
But he said he expected a "political negotiation and a sensible compromise".
On Friday the European Commission President Jose Manuel Barroso said the demand was made under a system agreed by all the member states.
EU finance ministers have agreed to the UK's request for emergency talks about the top-up payment, which would add about a fifth to the UK's net EU contribution of £8.6bn for this year.
The prime minister said on Friday he was "downright angry" and that the British public would find the "vast" sum "totally unacceptable".
He said: "It is an unacceptable way for this organisation to work - to suddenly present a bill like this for such a vast sum of money with so little time to pay it.
"It is an unacceptable way to treat a country which is one of the biggest contributors to the EU."