A row has erupted between Brighton Festival and the Brighton Fringe.
Organisers of the fringe, which has been running since 1996, say they were asked to hand over their database and join the festival in a steering committee.
But the fringe, which involves up to 1,000 artists each year, refused because it wants the event to stay independent.
Now Brighton Festival has announced it is renaming its self-programmed events, previously known as the Open and the Umbrella, The Brighton Festival Fringe.
Jeff Hemmings, director of the Brighton Fringe, which is independently funded, said it would be seeking legal advice.
He said: "This name change is totally unacceptable. I am extremely angry and disappointed. It is a direct challenge to what we are doing.
"The Brighton Festival has been giving the impression we are working with them. But that is not the case. We will not co-operate with them unless they agree to long-term plans for an independent fringe."
He said the fringe should be independent, as is the Edinburgh Fringe Festival, because it was important it was not reliant on funding from the council.
Mr Hemmings said: "At an initial meeting they asked us to close our fringe down, hand over our database and join some steering committee. We thought this was outrageous. Why should we close down our personal company which we have been running for six years?
"We said we would only consider joining forces if the fringe stayed independent. They said they could give no promises and even if it did happen, it would not be for a few years."
He said the renaming of the Brighton Festival's Umbrella event would only serve to increase public confusion, rather than reduce it as Brighton Festival hoped it would.
But according to Brighton Festival, the name change has already resulted in more than 500 inquiries from groups wanting to take part.
Nick Dodds, chief executive of Brighton Festival, said: "Our main aim is to upgrade the self-programme part of the festival and give it a higher profile. I believe passionately the two should sit side by side."
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article