Britain crashing out of the European single market could costbanks and associated businesses in the U.K. almost 40 billionpounds ($51 billion) in lost revenue, undermining a key sector ofthe economy, an industry report will warn on Wednesday.

Finance firms are making a fresh bid for special status inupcoming Brexit negotiations with the EU after U.K. governmentofficials this week indicated banks will get no favors. The report,prepared by Oliver Wyman on behalf of TheCityUK lobby group, warnsthat almost 70,000 jobs and 10 billion pounds of tax revenue are atrisk from a so-called hard Brexit, according to two people familiarwith its contents.

Prime Minister Theresa May has ruled out prioritizing protectionof the banks in Brexit talks and has dismissed their key businessdemand for an interim deal to help ease the transition out of thebloc, Bloomberg News reported Monday, citing three governmentofficials. Finance executives have threatened to move jobs ifBritain doesn't secure a deal allowing them to serve Europeanclients from London.