Small businesses in Britain plan the least investment in two years as uncertainty about Brexit drags on, a survey showed.

Nearly three quarters of small firms said they will not increase capital investment over the coming quarter, the survey by the Federation of Small Businesses found.

"It's impossible for small business owners to invest for the future when we don't know what the future holds," FSB National Chairman Mike Cherry said.

Businesses cut back on investment throughout 2018, official data has shown, the longest such run since the financial crisis a decade ago, raising concerns about damage to Britain's long-term growth prospects.

The FSB survey also found the net balance of small firms increasing staff was at a three-year low as employers struggled to find the right candidates with Britain's unemployment rate at its lowest in more than 40 years.