As many as 4,000 businesses in Northern Ireland could be victims of extortion.
The Federation of Small Businesses made the claim in evidence to MPs conducting an inquiry into organised crime in the province.
The Confederation of British Industry also appeared before the Northern Ireland Affairs Select Committee.
It said some construction companies paid up to £30,000 a year in protection money and there was little confidence in the police to help.
The FSB accused the government of making no real efforts to tackle extortion and called for a new help-line to be set up.
On Tuesday, Security Minister Shaun Woodward said he was delighted that the FSB, CBI, and the Northern Ireland Chamber of Commerce had joined the Organised Crime Task Force, which he chairs.
"I am confident that their contribution will significantly add to our collective response," he said.