Brexit is beginning to bite for tech startups, with a third of innovative firms saying they have lost a potential hire from outside the UK.
It comes just a day after the Prime Minister Theresa May promised an additional 1,000 visas for talented tech workers from outside the EU.
The new research comes from Tech London Advocates (TLA), which has more than 5,000 members who are startup founders.
More than half (55 per cent) said access to talent was the biggest threat to the flourishing sector, which May yesterday promised to help after hosting a roundtable with chancellor Philip Hammond with some of the UK's top entrepreneurs.
“The chancellor said government would be ambitious as it works to make the most of the incredible potential of the tech sector, to break down the barriers facing entrepreneurs and to drive future growth," said a Downing Street spokesperson of the private event.
But the TLA research found that 61 per cent of founders believe Brexit has already damaged London's international reputation as centre for tech, though a similar proportion said the capital was still the best place in Europe to start and scale the company.
“Entrepreneurs are defined by their ability to turn challenges into opportunities and the sentiment across London’s tech sector is increasingly one of determination, conviction and ambition," said TLA founder Russ Shaw.
"Slowing down access to European talent will make growing a tech company harder, but London is focused on strengthening its relationship with tech hubs across Europe and around the world that are already fuelling our investment pipeline.”
Earlier research suggests fewer foreign workers are considering coming to work in the UK as a result of the vote to leave the EU.