Firms are being held back by poor broadband links, with some looking to move their business elsewhere because of connection problems.
Some areas are said to be "plagued" by low-quality networks, making it difficult to even send emails to clients or customers.
The issue is preventing some firms from making business deals in this country and abroad.
The British Chambers of Commerce (BCC) said all businesses in the UK should be able to take for granted access to high quality and reliable broadband.
The business group said Doncaster was one area with poor digital connections, which was an "embarrassment" for companies.
Mathew Lynds, managing director at property management company Rejus, said: "It makes things very difficult when trying to trade internationally, and is a major problem for growth."
Nick Joels, a director at garden furniture firm Innovators International, based in Elstree, Hertfordshire, said he is looking to move his business elsewhere because broadband is so bad in his area.
John Longworth, director general of the BCC, said: "Broadband is as essential to the success of a business as any other form of infrastructure, as without it firms struggle with the simplest of tasks such as sending an email.
"But more fundamentally, it is holding them back from trading the world and making connections overseas. Too often, we hear from companies that the broadband in their area is unreliable, and that this is a key barrier to growing their business. This is unacceptable.
"We are in a digital age now where firms rely heavily on digital infrastructure to run their businesses day to day. Although there has been some progress in delivering quality broadband to parts of the country, more must be done to ensure that no business is left on the sidelines.
"We urge the Government to make high-quality broadband connectivity a top priority in the months ahead, and to work with industry to deliver it. It is essential that massive investment in digital connectivity must proceed even if overall government spending falls back, as without this businesses cannot fulfil their true potential."