Former Conservative party treasurer Michael Spencer has denounced efforts by some EU countries to strip London of key financial services after Brexit.

He said it was “a real nasty piece of economic nationalism and protectionism” to insist that euro-denominated deals should be settled in the EU.

Mr Spencer, chief executive of NEX Group, told the BBC that he had voted Remain in the June 2016 referendum.

However, he was now “fully signed up” to UK’s decision to leave the EU.

EU financial services commissioner Valdis Dombrovskis is arguing that either the EU should have greater policing powers over euro-clearing in London or the business should relocate to the EU.

The European Commission is set to rule on the matter next month.

Mr Spencer told BBC Radio 4’s Today programme: “This proposal by certain people in Europe to repatriate euro-clearing to the eurozone is nothing more than a real nasty piece of economic nationalism and protectionism.”

He added: “Logic would dictate that it’s in Europe’s interest to have a sensible agreement with the UK on financial services and not to seek to stupidly plunder, as some Europeans feel they can do, to try to plunder the UK’s financial services.

“Damaging London, in my opinion, will also damage Europe and I think it is in the interests, certainly of the UK but certainly of the EU as well, to make sure that London’s capability as a global financial centre remains properly intact and undamaged.”

Mr Spencer founded ICAP, which became NEX Group last year following the sale of part of the business.

Meanwhile, London Stock Exchange chief executive Xavier Rolet has warned Brussels that stripping London of its euro-clearing business could increase trading costs by 100bn euros.

He wrote in The Times that stopping London from processing trades in euro-denominated assets would “increase, not reduce, levels of systematic risk, and increase costs for European companies, diverting capital away from the European economy”.

Brussels has launched a consultation into the future rules in light of the UK’s impending departure from the EU.