In a plea to chancellor Alistair Darling ahead of the 2008 Budget, the federation cited evidence from a survey conducted by the Small Business Research Trust which suggested that trading conditions have declined in the areas of sales, employment and investment during the first quarter of this year.
This is reported to contrast with the "optimism" expressed by small companies at the end of last year.
FSB chief executive Phil Orford stated: "This government has undertaken a sustained attack on smaller businesses and their owners for too long.
"We are close to the tipping point where a sector that provides innovation and drive to the UK’s economy is going to be pushed into a long period of negative growth."
Established in 1977, the FSB represents around 25,000 private firms in the UK.
