London's status as the world's financial technology – or fintech– hub could be under threat should a Brexit occur, lawyers, venture capitalists and start-ups have warned CNBC.
As Britons head to the polls on Thursday to decide the future of the U.K.'s membership of the European Union (EU), technology market leaders have already noticed parts of their business slowing down given the uncertainty around the outcome of the referendum.
"We will see that other regions will grow stronger at the expense of the U.K. in the event of a Brexit," Andreas Haug, co-founder and partner at e.ventures, a venture capital firm with headquarters in Germany, told CNBC by phone.
"The fintech sector will take a huge hit. Teams in the U.K. are supported by the financial industry, and a constructive government and regulator, but if you can't roll your product out European-wide, a lot of teams will move away."
Technology firms benefit from a number of advantages from the U.K. being a member of the EU. Any business regulated by U.K. authorities can "passport" their products across the European Economic Area. Firms are concerned whether this might be disappear if a Brexit happens. Companies are also bound to a number of EU laws around data protection. And the European Commission is currently trying to push through the "Digital Single Market" agenda which aims to harmonize rules across the EU in areas such as copyright.