The big four Edinburgh Fringe venues have been accused of ‘divisive’ behaviour, after deciding to promote their own comedy festival.

The Assembly, Pleasance, Underbelly and Gilded Balloon venues are setting up the Edinburgh Comedy Festival this August, which will have its own brochure.

The move has sparked fears this will herald the start of a ‘breakaway’ festival that could damage the existing Fringe.

However they insist it is just a marketing device aimed at boosting audiences and attracting big-name sponsorship – which some have estimated could be worth up to £650,000.

The new comedy brochure will have a 400,000 print run, and with projected sales of more than 550,000 tickets, the Edinburgh Comedy Festival will be the largest comedy festival in the world.

However the move has caused consternation among fringe venues who are not part of the group.

Tommy Sheppard, director of the Stand Comedy Club, said: ‘It's very much a breakaway thing. It's a great shame they are taking such a divisive attitude. I know they're trying to form a cartel to lever more sponsorship.’

The 250 comedy shows at the big four venues this year would still appear in the main Fringe programme, as well as under the Edinburgh Comedy Festival banner, and tickets will be sold through the Fringe box office.

The charge for entry in the Fringe programme, and a small cut of ticket sales, funds the festival - so if a breakaway comedy event was formed, it could seriously damage the existing organisation.

However, the venues insist this is not their plan, saying it is ‘purely marketing attempt at increasing audiences figures at the Fringe’.

Launching their festival, William Burdett-Coutts of Assembly, Anthony Alderson of the Pleasance, Charlie Wood of the Underbelly and Karen Koren of the Gilded Balloon all reiterated their commitment to the Fringe

Burdett-Coutts said: ‘I think this is a welcome development that will give comedy the platform it deserves whilst also being a magnificent way of improving marketing for our collective programmes and the festival as a whole.’

Koren added that the comedy festival could include other venues in future years.

She said: ‘In this first year of the Edinburgh Comedy Festival we plan to establish the brand with our four venues. In future years we hope other Edinburgh Fringe venues will join the umbrella to market their programmes under this brilliant and exciting new festival.’

But such pledges will not reassured many critics.

One unnamed Fringe figure told The Scotsman today: ‘This is about setting up a festival within a festival and is potentially very divisive. Anybody who genuinely cares about comedy doesn't try to own it.’

Another said: ‘Having a joint programme is one thing, but promoting your shows as the Edinburgh Comedy Festival is something else completely. It's unfair on audiences and unfair on other venues.’