Mixed reviews, as some venues boom and others struggle to fill seats

• The Royal Mile with the Fringe in full swing

Although more tickets than ever before are expected to have been sold at the Fringe this year, thanks to the addition of several major new venues and a huge increase in shows, leading festival figures claim the Fringe "bubble" is in danger of bursting.

The Assembly Rooms, the Stand Comedy Club and the New Town Theatre have admitted that many shows have performed poorly this year, with a slump in audiences during the last week of the Fringe.

It is thought the Fringe could break the two million ticket sales barrier for the first time, after a 17 per cent increase in the number of shows taking part.

But veteran promoters believe the festival is now "over-capacity" for the first time due to the growth of some venues and have expressed concern that the recession has had more of an impact this year than last.

However, other venues around the university area in the south side — including Underbelly, Gilded Balloon, Pleasance and C Venues — are all thought to have had their strongest ever year, with many shows selling out entire runs.

Venue managers also revealed the Fringe has suffered a dramatic drop in audiences over the past seven days, since the end of the school holidays in Scotland, amid claims that fewer people are travelling north from England for the festival.

Tommy Sheppard, director of the Stand, claims venues with a large capacity should either be excluded from the Fringe programme or charged a much higher rate for entry.

Assembly impresario William Burdett-Coutts admitted that well-known theatre companies had struggled to fill shows, as audiences were being more careful with their money this year.

Laura Mackenzie Stuart, director of Universal Arts, which runs the New Town Theatre, said performing companies had to work "much hard than normal" to attract audiences this year, and said ticket sales would almost certainly be down.

This year's Fringe boasted 2,453 shows, compared with 1,350 in the programme ten years ago.About 1.859 million tickets were sold for Fringe shows last year, a 9 per cent increase on the previous record, set in 2007.

Although many festival observers believe the Assembly, which expanded into a major new venue in Princes Street Gardens, has struggled to attract audiences, Mr Burdett-Coutts said he was still on course to sell more tickets than ever before.

But he added: "I do think the Fringe has hit a bit of a limit this year. The balloon has extended as far it can go audience-wise, and what we're seeing is some venues getting bigger audiences while others are going down.

"It's been extremely hard to get audiences into some of our big theatre productions and I think the Fringe has hit a bit of customer resistance over the price of tickets.

"There's definitely been a cheap-ticket culture around and people just don't seem to have had the same money.

"We are going to lose money on Princes Street Gardens, but that was probably always going to be the case in the first year. Some shows there have been very quiet mid-week, but we're very committed to doing it again next year."

Mr Sheppard said: "There is too much venue capacity now. If you add an extra 100,000 seats to the Fringe it is going to have an impact on other venues.

"We have become more and more reliant on a local audience, and that drops down significantly when the schools go back. We're just not getting the huge numbers of people coming to the last week of the Fringe from London.

"What we have seen is the creation of an entertainment vortex around Edinburgh University, which is sucking people away from other venues. A lot of them will just be sitting around drinking for hours, but that is still generating a phenomenal amount of money for these venues."

Ms Mackenzie Stuart said: "It has been quieter for us this year. People have been a bit more careful with their money and seem to have been very cautious about what to see. The recession seems to have had more of an impact this year."

The Fringe is expected to reveal its official box office figures later today, after the first full year of chief executive Kath Mainland's tenure.

Hartley Kemp, artistic director at C Venues, which expanded into a number of new sites this year, said: "Our ticket sales are up about 25 per cent on last year and I'm delighted with how things have gone.

"People are booking on the strength of the programme and there is a definite trend of booking much earlier in advance."

Anthony Alderson, artistic director at the Pleasance venues, said: "We have had an absolutely fantastic festival, definitely our strongest ever for ticket sales and everything seems to have gone right.

"I don't believe the Fringe is at capacity. We were hearing complaints about it becoming too big ten years ago and yet ticket sales have kept going up."

Karen Koren, artistic director at Gilded Balloon, added: "We've definitely had record ticket sales at Teviot."