A lack of talent and strict immigration policies are holding back London's tech sector, according to a group of business experts.
The claims came to light after Tech London Advocates, a coalition of individuals from government, technology and business that champion London's potential as a hub for tech and digital businesses, asked 173 of its members, which includes people what they consider to London's greatest hurdles to continued growth.
The organisation found 43 percent of those surveyed see a lack of talent as the main problem, while 10 percent see immigration legislation as the biggest issue.
Indeed, it can take months for tech companies to get through the visa process and hire highly skilled migrant workers. In the tech world, this is often too long, according to Tech London Advocates founder, Russ Shaw.
"A lack of skills and challenging immigration legislation is inhibiting growth in the capital and threatening London's position as a global technology hub," he said.
"Encouraging young people to study STEM (science, technology, education and maths) subjects and initiatives to encourage digital skills are important steps in the right direction but we are calling on the government to review education and immigration legislation to fuel the long term growth of London's most vibrant industry."
Nearly all of those surveyed said they were experiencing difficulties around recruitment despite having, on average, seven open vacancies.
Leslie Sarma, associate at Penningtons Manches law firm and Tech London Advocates immigration working group lead, said: "We believe there is still work to be done in assisting rapid growth start-ups looking to staff up quickly. The expansion of Tier 1 (Exceptional Talent) to the tech sector is an excellent step, and we look forward to continued work with the Home Office to facilitate growth across the digital technology community throughout the UK."
Dan Crow, CTO of music news provider Songkick, said his company has found it hard to get highly skilled people from outside the EU.
"There is a deep pool of highly experienced people in Silicon Valley," he said. "We've managed to tempt a few of them to London, but we've also lost some very promising potential employees because it is so hard for Americans to get work visas for the UK."