LONDON (Reuters) - Prime Minister Theresa May faced a backlash on Wednesday from prominent supporters of Brexit after reports that she is ready to pay much of what the European Union is demanding to settle the country s  divorce bill  to leave the bloc. The Daily Telegraph newspaper said the net bill would total 45 billion to 55 billion pounds ($53 billion to $65 billion). A government official cast doubt on those numbers and the European Commission declined to comment, but there is a growing expectation that the sides will clinch a deal on cash. Veteran Brexit campaigner Nigel Farage said Britain should walk away from the talks rather than offer such huge sums.  This is a complete sell-out that is not in our national interest,  said Farage, a former leader of the UK Independence Party (UKIP) who played a big role in the 2016 referendum in which 52 percent of Britons voted to leave the EU.  The British prime minister needs to say:  Look, either start to behave reasonably, either start to behave in a grown-up way, or ... we are walking away ,  Farage, who remains a member of the European Parliament, told Reuters. Many businesses and investors fear such an approach, leading to a  disorderly Brexit , would spook financial markets, sow legal chaos and badly harm the British and EU economies by disrupting trade ties and cross-border supply chains. Farage and pro-Brexit entrepreneurs such as billionaire Peter Hargreaves say Britain can prosper outside the EU and what they see as its onerous rules and regulations. Britain, which is due to leave in March 2019, hopes to persuade EU leaders next month that the sides have made enough progress on three key issues - the rights of EU citizens living in the UK, the exit bill and the land border with Ireland - to be able to move on to talks on a post-Brexit trade relationship. Hardline Brexit supporters in May s ruling Conservative Party have been fairly muted in recent weeks on the money issue, with British media saying the cabinet had swung behind her plans to pay more in the exit bill. On Wednesday Foreign Secretary Boris Johnson, one of the leaders of the 2016  Leave  campaign, said it was  time to get the ship off the rocks .  But Hargreaves, the second biggest donor to last year s Leave campaign, denounced the government s handling of Brexit talks, saying they showed no understanding of the sums involved.  We ought to say to the EU:  Thank you very much, we are never going to get a deal, goodbye  and we are gone, lock stock and barrel, and carry on trading as before,  Hargreaves said. Farage dismissed calls by some opponents of Brexit such as former prime minister Tony Blair that British voters might change their mind about leaving the EU.  The revolution of 2016 is still rolling,  he said.  The European Union project is in deep trouble and it s only a matter of time until it ends.  The EU s supporters say it has helped to cement peace, prosperity and stability across a continent historically ravaged by wars. Farage s opponents see him and his party - now riven by divisions and with no lawmakers in the British parliament - as dangerous populists who misled voters about the true costs of Brexit. ($1 = 0.8433 euros) (Adds information in signoff field) 
Brexit campaigners accuse May of selling UK short over divorce bill