Pub landlords want to call time on being "tied" to a large company for their beer and other supplies, according to a new study.
A survey of 500 tenants tied to the so-called pubcos showed that most believed the firms were taking too much of their profits.
Almost two-thirds of those questioned by the Federation of Small Businesses (FSB) said they would stock a greater range of beers and nine out of 10 would approach microbreweries for products if they could.
The FSB said the research showed that a statutory code being planned for the industry could not be brought in soon enough.
Chairman John Allan said: " The big pubcos are as bad as each other and their tenants don't feel they are getting a fair deal. They want to give their punters more choice as well as interesting craft beers too.
"The largest pub companies are able to control the relationships to their own advantage and are under pressure to reduce their debts by increasing income from rent and selling off pubs.
"Considering current conditions we believe that it is not possible for the large pub companies to operate credible voluntary regulation."
A Business Department spokesman said: "We are currently considering all the responses to the consultation alongside other evidence, such as the independent research we commissioned into the potential impact of the proposals on pub closures and employments levels. We will publish our response to the consultation later this year."